Documentation / git-rebase.txton commit docs: clarify what git-rebase's "-p" / "--preserve-merges" does (d50d31e)
   1git-rebase(1)
   2=============
   3
   4NAME
   5----
   6git-rebase - Forward-port local commits to the updated upstream head
   7
   8SYNOPSIS
   9--------
  10[verse]
  11'git rebase' [-i | --interactive] [options] [--exec <cmd>] [--onto <newbase>]
  12        [<upstream>] [<branch>]
  13'git rebase' [-i | --interactive] [options] [--exec <cmd>] [--onto <newbase>]
  14        --root [<branch>]
  15'git rebase' --continue | --skip | --abort | --edit-todo
  16
  17DESCRIPTION
  18-----------
  19If <branch> is specified, 'git rebase' will perform an automatic
  20`git checkout <branch>` before doing anything else.  Otherwise
  21it remains on the current branch.
  22
  23If <upstream> is not specified, the upstream configured in
  24branch.<name>.remote and branch.<name>.merge options will be used; see
  25linkgit:git-config[1] for details.  If you are currently not on any
  26branch or if the current branch does not have a configured upstream,
  27the rebase will abort.
  28
  29All changes made by commits in the current branch but that are not
  30in <upstream> are saved to a temporary area.  This is the same set
  31of commits that would be shown by `git log <upstream>..HEAD` (or
  32`git log HEAD`, if --root is specified).
  33
  34The current branch is reset to <upstream>, or <newbase> if the
  35--onto option was supplied.  This has the exact same effect as
  36`git reset --hard <upstream>` (or <newbase>).  ORIG_HEAD is set
  37to point at the tip of the branch before the reset.
  38
  39The commits that were previously saved into the temporary area are
  40then reapplied to the current branch, one by one, in order. Note that
  41any commits in HEAD which introduce the same textual changes as a commit
  42in HEAD..<upstream> are omitted (i.e., a patch already accepted upstream
  43with a different commit message or timestamp will be skipped).
  44
  45It is possible that a merge failure will prevent this process from being
  46completely automatic.  You will have to resolve any such merge failure
  47and run `git rebase --continue`.  Another option is to bypass the commit
  48that caused the merge failure with `git rebase --skip`.  To check out the
  49original <branch> and remove the .git/rebase-apply working files, use the
  50command `git rebase --abort` instead.
  51
  52Assume the following history exists and the current branch is "topic":
  53
  54------------
  55          A---B---C topic
  56         /
  57    D---E---F---G master
  58------------
  59
  60From this point, the result of either of the following commands:
  61
  62
  63    git rebase master
  64    git rebase master topic
  65
  66would be:
  67
  68------------
  69                  A'--B'--C' topic
  70                 /
  71    D---E---F---G master
  72------------
  73
  74*NOTE:* The latter form is just a short-hand of `git checkout topic`
  75followed by `git rebase master`. When rebase exits `topic` will
  76remain the checked-out branch.
  77
  78If the upstream branch already contains a change you have made (e.g.,
  79because you mailed a patch which was applied upstream), then that commit
  80will be skipped. For example, running `git rebase master` on the
  81following history (in which A' and A introduce the same set of changes,
  82but have different committer information):
  83
  84------------
  85          A---B---C topic
  86         /
  87    D---E---A'---F master
  88------------
  89
  90will result in:
  91
  92------------
  93                   B'---C' topic
  94                  /
  95    D---E---A'---F master
  96------------
  97
  98Here is how you would transplant a topic branch based on one
  99branch to another, to pretend that you forked the topic branch
 100from the latter branch, using `rebase --onto`.
 101
 102First let's assume your 'topic' is based on branch 'next'.
 103For example, a feature developed in 'topic' depends on some
 104functionality which is found in 'next'.
 105
 106------------
 107    o---o---o---o---o  master
 108         \
 109          o---o---o---o---o  next
 110                           \
 111                            o---o---o  topic
 112------------
 113
 114We want to make 'topic' forked from branch 'master'; for example,
 115because the functionality on which 'topic' depends was merged into the
 116more stable 'master' branch. We want our tree to look like this:
 117
 118------------
 119    o---o---o---o---o  master
 120        |            \
 121        |             o'--o'--o'  topic
 122         \
 123          o---o---o---o---o  next
 124------------
 125
 126We can get this using the following command:
 127
 128    git rebase --onto master next topic
 129
 130
 131Another example of --onto option is to rebase part of a
 132branch.  If we have the following situation:
 133
 134------------
 135                            H---I---J topicB
 136                           /
 137                  E---F---G  topicA
 138                 /
 139    A---B---C---D  master
 140------------
 141
 142then the command
 143
 144    git rebase --onto master topicA topicB
 145
 146would result in:
 147
 148------------
 149                 H'--I'--J'  topicB
 150                /
 151                | E---F---G  topicA
 152                |/
 153    A---B---C---D  master
 154------------
 155
 156This is useful when topicB does not depend on topicA.
 157
 158A range of commits could also be removed with rebase.  If we have
 159the following situation:
 160
 161------------
 162    E---F---G---H---I---J  topicA
 163------------
 164
 165then the command
 166
 167    git rebase --onto topicA~5 topicA~3 topicA
 168
 169would result in the removal of commits F and G:
 170
 171------------
 172    E---H'---I'---J'  topicA
 173------------
 174
 175This is useful if F and G were flawed in some way, or should not be
 176part of topicA.  Note that the argument to --onto and the <upstream>
 177parameter can be any valid commit-ish.
 178
 179In case of conflict, 'git rebase' will stop at the first problematic commit
 180and leave conflict markers in the tree.  You can use 'git diff' to locate
 181the markers (<<<<<<) and make edits to resolve the conflict.  For each
 182file you edit, you need to tell Git that the conflict has been resolved,
 183typically this would be done with
 184
 185
 186    git add <filename>
 187
 188
 189After resolving the conflict manually and updating the index with the
 190desired resolution, you can continue the rebasing process with
 191
 192
 193    git rebase --continue
 194
 195
 196Alternatively, you can undo the 'git rebase' with
 197
 198
 199    git rebase --abort
 200
 201CONFIGURATION
 202-------------
 203
 204rebase.stat::
 205        Whether to show a diffstat of what changed upstream since the last
 206        rebase. False by default.
 207
 208rebase.autosquash::
 209        If set to true enable '--autosquash' option by default.
 210
 211rebase.autostash::
 212        If set to true enable '--autostash' option by default.
 213
 214OPTIONS
 215-------
 216--onto <newbase>::
 217        Starting point at which to create the new commits. If the
 218        --onto option is not specified, the starting point is
 219        <upstream>.  May be any valid commit, and not just an
 220        existing branch name.
 221+
 222As a special case, you may use "A\...B" as a shortcut for the
 223merge base of A and B if there is exactly one merge base. You can
 224leave out at most one of A and B, in which case it defaults to HEAD.
 225
 226<upstream>::
 227        Upstream branch to compare against.  May be any valid commit,
 228        not just an existing branch name. Defaults to the configured
 229        upstream for the current branch.
 230
 231<branch>::
 232        Working branch; defaults to HEAD.
 233
 234--continue::
 235        Restart the rebasing process after having resolved a merge conflict.
 236
 237--abort::
 238        Abort the rebase operation and reset HEAD to the original
 239        branch. If <branch> was provided when the rebase operation was
 240        started, then HEAD will be reset to <branch>. Otherwise HEAD
 241        will be reset to where it was when the rebase operation was
 242        started.
 243
 244--keep-empty::
 245        Keep the commits that do not change anything from its
 246        parents in the result.
 247
 248--skip::
 249        Restart the rebasing process by skipping the current patch.
 250
 251--edit-todo::
 252        Edit the todo list during an interactive rebase.
 253
 254-m::
 255--merge::
 256        Use merging strategies to rebase.  When the recursive (default) merge
 257        strategy is used, this allows rebase to be aware of renames on the
 258        upstream side.
 259+
 260Note that a rebase merge works by replaying each commit from the working
 261branch on top of the <upstream> branch.  Because of this, when a merge
 262conflict happens, the side reported as 'ours' is the so-far rebased
 263series, starting with <upstream>, and 'theirs' is the working branch.  In
 264other words, the sides are swapped.
 265
 266-s <strategy>::
 267--strategy=<strategy>::
 268        Use the given merge strategy.
 269        If there is no `-s` option 'git merge-recursive' is used
 270        instead.  This implies --merge.
 271+
 272Because 'git rebase' replays each commit from the working branch
 273on top of the <upstream> branch using the given strategy, using
 274the 'ours' strategy simply discards all patches from the <branch>,
 275which makes little sense.
 276
 277-X <strategy-option>::
 278--strategy-option=<strategy-option>::
 279        Pass the <strategy-option> through to the merge strategy.
 280        This implies `--merge` and, if no strategy has been
 281        specified, `-s recursive`.  Note the reversal of 'ours' and
 282        'theirs' as noted above for the `-m` option.
 283
 284-S[<keyid>]::
 285--gpg-sign[=<keyid>]::
 286        GPG-sign commits.
 287
 288-q::
 289--quiet::
 290        Be quiet. Implies --no-stat.
 291
 292-v::
 293--verbose::
 294        Be verbose. Implies --stat.
 295
 296--stat::
 297        Show a diffstat of what changed upstream since the last rebase. The
 298        diffstat is also controlled by the configuration option rebase.stat.
 299
 300-n::
 301--no-stat::
 302        Do not show a diffstat as part of the rebase process.
 303
 304--no-verify::
 305        This option bypasses the pre-rebase hook.  See also linkgit:githooks[5].
 306
 307--verify::
 308        Allows the pre-rebase hook to run, which is the default.  This option can
 309        be used to override --no-verify.  See also linkgit:githooks[5].
 310
 311-C<n>::
 312        Ensure at least <n> lines of surrounding context match before
 313        and after each change.  When fewer lines of surrounding
 314        context exist they all must match.  By default no context is
 315        ever ignored.
 316
 317-f::
 318--force-rebase::
 319        Force the rebase even if the current branch is a descendant
 320        of the commit you are rebasing onto.  Normally non-interactive rebase will
 321        exit with the message "Current branch is up to date" in such a
 322        situation.
 323        Incompatible with the --interactive option.
 324+
 325You may find this (or --no-ff with an interactive rebase) helpful after
 326reverting a topic branch merge, as this option recreates the topic branch with
 327fresh commits so it can be remerged successfully without needing to "revert
 328the reversion" (see the
 329link:howto/revert-a-faulty-merge.html[revert-a-faulty-merge How-To] for details).
 330
 331--fork-point::
 332--no-fork-point::
 333        Use 'git merge-base --fork-point' to find a better common ancestor
 334        between `upstream` and `branch` when calculating which commits have
 335        have been introduced by `branch` (see linkgit:git-merge-base[1]).
 336+
 337If no non-option arguments are given on the command line, then the default is
 338`--fork-point @{u}` otherwise the `upstream` argument is interpreted literally
 339unless the `--fork-point` option is specified.
 340
 341--ignore-whitespace::
 342--whitespace=<option>::
 343        These flag are passed to the 'git apply' program
 344        (see linkgit:git-apply[1]) that applies the patch.
 345        Incompatible with the --interactive option.
 346
 347--committer-date-is-author-date::
 348--ignore-date::
 349        These flags are passed to 'git am' to easily change the dates
 350        of the rebased commits (see linkgit:git-am[1]).
 351        Incompatible with the --interactive option.
 352
 353-i::
 354--interactive::
 355        Make a list of the commits which are about to be rebased.  Let the
 356        user edit that list before rebasing.  This mode can also be used to
 357        split commits (see SPLITTING COMMITS below).
 358
 359-p::
 360--preserve-merges::
 361        Recreate merge commits instead of flattening the history by replaying
 362        commits a merge commit introduces. Merge conflict resolutions or manual
 363        amendments to merge commits are not preserved.
 364+
 365This uses the `--interactive` machinery internally, but combining it
 366with the `--interactive` option explicitly is generally not a good
 367idea unless you know what you are doing (see BUGS below).
 368
 369-x <cmd>::
 370--exec <cmd>::
 371        Append "exec <cmd>" after each line creating a commit in the
 372        final history. <cmd> will be interpreted as one or more shell
 373        commands.
 374+
 375This option can only be used with the `--interactive` option
 376(see INTERACTIVE MODE below).
 377+
 378You may execute several commands by either using one instance of `--exec`
 379with several commands:
 380+
 381        git rebase -i --exec "cmd1 && cmd2 && ..."
 382+
 383or by giving more than one `--exec`:
 384+
 385        git rebase -i --exec "cmd1" --exec "cmd2" --exec ...
 386+
 387If `--autosquash` is used, "exec" lines will not be appended for
 388the intermediate commits, and will only appear at the end of each
 389squash/fixup series.
 390
 391--root::
 392        Rebase all commits reachable from <branch>, instead of
 393        limiting them with an <upstream>.  This allows you to rebase
 394        the root commit(s) on a branch.  When used with --onto, it
 395        will skip changes already contained in <newbase> (instead of
 396        <upstream>) whereas without --onto it will operate on every change.
 397        When used together with both --onto and --preserve-merges,
 398        'all' root commits will be rewritten to have <newbase> as parent
 399        instead.
 400
 401--autosquash::
 402--no-autosquash::
 403        When the commit log message begins with "squash! ..." (or
 404        "fixup! ..."), and there is a commit whose title begins with
 405        the same ..., automatically modify the todo list of rebase -i
 406        so that the commit marked for squashing comes right after the
 407        commit to be modified, and change the action of the moved
 408        commit from `pick` to `squash` (or `fixup`).  Ignores subsequent
 409        "fixup! " or "squash! " after the first, in case you referred to an
 410        earlier fixup/squash with `git commit --fixup/--squash`.
 411+
 412This option is only valid when the '--interactive' option is used.
 413+
 414If the '--autosquash' option is enabled by default using the
 415configuration variable `rebase.autosquash`, this option can be
 416used to override and disable this setting.
 417
 418--[no-]autostash::
 419        Automatically create a temporary stash before the operation
 420        begins, and apply it after the operation ends.  This means
 421        that you can run rebase on a dirty worktree.  However, use
 422        with care: the final stash application after a successful
 423        rebase might result in non-trivial conflicts.
 424
 425--no-ff::
 426        With --interactive, cherry-pick all rebased commits instead of
 427        fast-forwarding over the unchanged ones.  This ensures that the
 428        entire history of the rebased branch is composed of new commits.
 429+
 430Without --interactive, this is a synonym for --force-rebase.
 431+
 432You may find this helpful after reverting a topic branch merge, as this option
 433recreates the topic branch with fresh commits so it can be remerged
 434successfully without needing to "revert the reversion" (see the
 435link:howto/revert-a-faulty-merge.html[revert-a-faulty-merge How-To] for details).
 436
 437include::merge-strategies.txt[]
 438
 439NOTES
 440-----
 441
 442You should understand the implications of using 'git rebase' on a
 443repository that you share.  See also RECOVERING FROM UPSTREAM REBASE
 444below.
 445
 446When the git-rebase command is run, it will first execute a "pre-rebase"
 447hook if one exists.  You can use this hook to do sanity checks and
 448reject the rebase if it isn't appropriate.  Please see the template
 449pre-rebase hook script for an example.
 450
 451Upon completion, <branch> will be the current branch.
 452
 453INTERACTIVE MODE
 454----------------
 455
 456Rebasing interactively means that you have a chance to edit the commits
 457which are rebased.  You can reorder the commits, and you can
 458remove them (weeding out bad or otherwise unwanted patches).
 459
 460The interactive mode is meant for this type of workflow:
 461
 4621. have a wonderful idea
 4632. hack on the code
 4643. prepare a series for submission
 4654. submit
 466
 467where point 2. consists of several instances of
 468
 469a) regular use
 470
 471 1. finish something worthy of a commit
 472 2. commit
 473
 474b) independent fixup
 475
 476 1. realize that something does not work
 477 2. fix that
 478 3. commit it
 479
 480Sometimes the thing fixed in b.2. cannot be amended to the not-quite
 481perfect commit it fixes, because that commit is buried deeply in a
 482patch series.  That is exactly what interactive rebase is for: use it
 483after plenty of "a"s and "b"s, by rearranging and editing
 484commits, and squashing multiple commits into one.
 485
 486Start it with the last commit you want to retain as-is:
 487
 488        git rebase -i <after-this-commit>
 489
 490An editor will be fired up with all the commits in your current branch
 491(ignoring merge commits), which come after the given commit.  You can
 492reorder the commits in this list to your heart's content, and you can
 493remove them.  The list looks more or less like this:
 494
 495-------------------------------------------
 496pick deadbee The oneline of this commit
 497pick fa1afe1 The oneline of the next commit
 498...
 499-------------------------------------------
 500
 501The oneline descriptions are purely for your pleasure; 'git rebase' will
 502not look at them but at the commit names ("deadbee" and "fa1afe1" in this
 503example), so do not delete or edit the names.
 504
 505By replacing the command "pick" with the command "edit", you can tell
 506'git rebase' to stop after applying that commit, so that you can edit
 507the files and/or the commit message, amend the commit, and continue
 508rebasing.
 509
 510If you just want to edit the commit message for a commit, replace the
 511command "pick" with the command "reword".
 512
 513If you want to fold two or more commits into one, replace the command
 514"pick" for the second and subsequent commits with "squash" or "fixup".
 515If the commits had different authors, the folded commit will be
 516attributed to the author of the first commit.  The suggested commit
 517message for the folded commit is the concatenation of the commit
 518messages of the first commit and of those with the "squash" command,
 519but omits the commit messages of commits with the "fixup" command.
 520
 521'git rebase' will stop when "pick" has been replaced with "edit" or
 522when a command fails due to merge errors. When you are done editing
 523and/or resolving conflicts you can continue with `git rebase --continue`.
 524
 525For example, if you want to reorder the last 5 commits, such that what
 526was HEAD~4 becomes the new HEAD. To achieve that, you would call
 527'git rebase' like this:
 528
 529----------------------
 530$ git rebase -i HEAD~5
 531----------------------
 532
 533And move the first patch to the end of the list.
 534
 535You might want to preserve merges, if you have a history like this:
 536
 537------------------
 538           X
 539            \
 540         A---M---B
 541        /
 542---o---O---P---Q
 543------------------
 544
 545Suppose you want to rebase the side branch starting at "A" to "Q". Make
 546sure that the current HEAD is "B", and call
 547
 548-----------------------------
 549$ git rebase -i -p --onto Q O
 550-----------------------------
 551
 552Reordering and editing commits usually creates untested intermediate
 553steps.  You may want to check that your history editing did not break
 554anything by running a test, or at least recompiling at intermediate
 555points in history by using the "exec" command (shortcut "x").  You may
 556do so by creating a todo list like this one:
 557
 558-------------------------------------------
 559pick deadbee Implement feature XXX
 560fixup f1a5c00 Fix to feature XXX
 561exec make
 562pick c0ffeee The oneline of the next commit
 563edit deadbab The oneline of the commit after
 564exec cd subdir; make test
 565...
 566-------------------------------------------
 567
 568The interactive rebase will stop when a command fails (i.e. exits with
 569non-0 status) to give you an opportunity to fix the problem. You can
 570continue with `git rebase --continue`.
 571
 572The "exec" command launches the command in a shell (the one specified
 573in `$SHELL`, or the default shell if `$SHELL` is not set), so you can
 574use shell features (like "cd", ">", ";" ...). The command is run from
 575the root of the working tree.
 576
 577----------------------------------
 578$ git rebase -i --exec "make test"
 579----------------------------------
 580
 581This command lets you check that intermediate commits are compilable.
 582The todo list becomes like that:
 583
 584--------------------
 585pick 5928aea one
 586exec make test
 587pick 04d0fda two
 588exec make test
 589pick ba46169 three
 590exec make test
 591pick f4593f9 four
 592exec make test
 593--------------------
 594
 595SPLITTING COMMITS
 596-----------------
 597
 598In interactive mode, you can mark commits with the action "edit".  However,
 599this does not necessarily mean that 'git rebase' expects the result of this
 600edit to be exactly one commit.  Indeed, you can undo the commit, or you can
 601add other commits.  This can be used to split a commit into two:
 602
 603- Start an interactive rebase with `git rebase -i <commit>^`, where
 604  <commit> is the commit you want to split.  In fact, any commit range
 605  will do, as long as it contains that commit.
 606
 607- Mark the commit you want to split with the action "edit".
 608
 609- When it comes to editing that commit, execute `git reset HEAD^`.  The
 610  effect is that the HEAD is rewound by one, and the index follows suit.
 611  However, the working tree stays the same.
 612
 613- Now add the changes to the index that you want to have in the first
 614  commit.  You can use `git add` (possibly interactively) or
 615  'git gui' (or both) to do that.
 616
 617- Commit the now-current index with whatever commit message is appropriate
 618  now.
 619
 620- Repeat the last two steps until your working tree is clean.
 621
 622- Continue the rebase with `git rebase --continue`.
 623
 624If you are not absolutely sure that the intermediate revisions are
 625consistent (they compile, pass the testsuite, etc.) you should use
 626'git stash' to stash away the not-yet-committed changes
 627after each commit, test, and amend the commit if fixes are necessary.
 628
 629
 630RECOVERING FROM UPSTREAM REBASE
 631-------------------------------
 632
 633Rebasing (or any other form of rewriting) a branch that others have
 634based work on is a bad idea: anyone downstream of it is forced to
 635manually fix their history.  This section explains how to do the fix
 636from the downstream's point of view.  The real fix, however, would be
 637to avoid rebasing the upstream in the first place.
 638
 639To illustrate, suppose you are in a situation where someone develops a
 640'subsystem' branch, and you are working on a 'topic' that is dependent
 641on this 'subsystem'.  You might end up with a history like the
 642following:
 643
 644------------
 645    o---o---o---o---o---o---o---o---o  master
 646         \
 647          o---o---o---o---o  subsystem
 648                           \
 649                            *---*---*  topic
 650------------
 651
 652If 'subsystem' is rebased against 'master', the following happens:
 653
 654------------
 655    o---o---o---o---o---o---o---o  master
 656         \                       \
 657          o---o---o---o---o       o'--o'--o'--o'--o'  subsystem
 658                           \
 659                            *---*---*  topic
 660------------
 661
 662If you now continue development as usual, and eventually merge 'topic'
 663to 'subsystem', the commits from 'subsystem' will remain duplicated forever:
 664
 665------------
 666    o---o---o---o---o---o---o---o  master
 667         \                       \
 668          o---o---o---o---o       o'--o'--o'--o'--o'--M  subsystem
 669                           \                         /
 670                            *---*---*-..........-*--*  topic
 671------------
 672
 673Such duplicates are generally frowned upon because they clutter up
 674history, making it harder to follow.  To clean things up, you need to
 675transplant the commits on 'topic' to the new 'subsystem' tip, i.e.,
 676rebase 'topic'.  This becomes a ripple effect: anyone downstream from
 677'topic' is forced to rebase too, and so on!
 678
 679There are two kinds of fixes, discussed in the following subsections:
 680
 681Easy case: The changes are literally the same.::
 682
 683        This happens if the 'subsystem' rebase was a simple rebase and
 684        had no conflicts.
 685
 686Hard case: The changes are not the same.::
 687
 688        This happens if the 'subsystem' rebase had conflicts, or used
 689        `--interactive` to omit, edit, squash, or fixup commits; or
 690        if the upstream used one of `commit --amend`, `reset`, or
 691        `filter-branch`.
 692
 693
 694The easy case
 695~~~~~~~~~~~~~
 696
 697Only works if the changes (patch IDs based on the diff contents) on
 698'subsystem' are literally the same before and after the rebase
 699'subsystem' did.
 700
 701In that case, the fix is easy because 'git rebase' knows to skip
 702changes that are already present in the new upstream.  So if you say
 703(assuming you're on 'topic')
 704------------
 705    $ git rebase subsystem
 706------------
 707you will end up with the fixed history
 708------------
 709    o---o---o---o---o---o---o---o  master
 710                                 \
 711                                  o'--o'--o'--o'--o'  subsystem
 712                                                   \
 713                                                    *---*---*  topic
 714------------
 715
 716
 717The hard case
 718~~~~~~~~~~~~~
 719
 720Things get more complicated if the 'subsystem' changes do not exactly
 721correspond to the ones before the rebase.
 722
 723NOTE: While an "easy case recovery" sometimes appears to be successful
 724      even in the hard case, it may have unintended consequences.  For
 725      example, a commit that was removed via `git rebase
 726      --interactive` will be **resurrected**!
 727
 728The idea is to manually tell 'git rebase' "where the old 'subsystem'
 729ended and your 'topic' began", that is, what the old merge-base
 730between them was.  You will have to find a way to name the last commit
 731of the old 'subsystem', for example:
 732
 733* With the 'subsystem' reflog: after 'git fetch', the old tip of
 734  'subsystem' is at `subsystem@{1}`.  Subsequent fetches will
 735  increase the number.  (See linkgit:git-reflog[1].)
 736
 737* Relative to the tip of 'topic': knowing that your 'topic' has three
 738  commits, the old tip of 'subsystem' must be `topic~3`.
 739
 740You can then transplant the old `subsystem..topic` to the new tip by
 741saying (for the reflog case, and assuming you are on 'topic' already):
 742------------
 743    $ git rebase --onto subsystem subsystem@{1}
 744------------
 745
 746The ripple effect of a "hard case" recovery is especially bad:
 747'everyone' downstream from 'topic' will now have to perform a "hard
 748case" recovery too!
 749
 750BUGS
 751----
 752The todo list presented by `--preserve-merges --interactive` does not
 753represent the topology of the revision graph.  Editing commits and
 754rewording their commit messages should work fine, but attempts to
 755reorder commits tend to produce counterintuitive results.
 756
 757For example, an attempt to rearrange
 758------------
 7591 --- 2 --- 3 --- 4 --- 5
 760------------
 761to
 762------------
 7631 --- 2 --- 4 --- 3 --- 5
 764------------
 765by moving the "pick 4" line will result in the following history:
 766------------
 767        3
 768       /
 7691 --- 2 --- 4 --- 5
 770------------
 771
 772GIT
 773---
 774Part of the linkgit:git[1] suite