user-manual: use pithier example commit

diff --git a/Documentation/git-repack.txt b/Documentation/git-repack.txt
index 49f7e0a4a446b8e393b76f39136f28c74c085dff..c57013b9537f68fafdb1c1d90491ff5d556ed326 100644 (file)
--- a/Documentation/git-repack.txt
+++ b/Documentation/git-repack.txt
@@ -3,8 +3,7 @@ git-repack(1)
 
 NAME
 ----
-git-repack - Script used to pack a repository from a collection of
-objects into pack files.
+git-repack - Pack unpacked objects in a repository
 
 
 SYNOPSIS
@@ -15,7 +14,8 @@ DESCRIPTION
 -----------
 
 This script is used to combine all objects that do not currently
-reside in a "pack", into a pack.
+reside in a "pack", into a pack.  It can also be used to re-organise
+existing packs into a single, more efficient pack.
 
 A pack is a collection of objects, individually compressed, with
 delta compression applied, stored in a single file, with an
@@ -29,11 +29,13 @@ OPTIONS
 
 -a::
        Instead of incrementally packing the unpacked objects,
-       pack everything available into a single pack.
+       pack everything referenced into a single pack.
        Especially useful when packing a repository that is used
-       for a private development and there no need to worry
+       for private development and there is no need to worry
        about people fetching via dumb protocols from it.  Use
-       with '-d'.
+       with '-d'.  This will clean up the objects that `git prune`
+       leaves behind, but `git fsck --full` shows as
+       dangling.
 
 -d::
        After packing, if the newly created packs make some
@@ -57,13 +59,28 @@ OPTIONS
         `git update-server-info`.
 
 --window=[N], --depth=[N]::
-       These two options affects how the objects contained in the pack are
+       These two options affect how the objects contained in the pack are
        stored using delta compression. The objects are first internally
        sorted by type, size and optionally names and compared against the
        other objects within `--window` to see if using delta compression saves
        space. `--depth` limits the maximum delta depth; making it too deep
        affects the performance on the unpacker side, because delta data needs
        to be applied that many times to get to the necessary object.
+       The default value for --window is 10 and --depth is 50.
+
+
+Configuration
+-------------
+
+When configuration variable `repack.UseDeltaBaseOffset` is set
+for the repository, the command passes `--delta-base-offset`
+option to `git-pack-objects`; this typically results in slightly
+smaller packs, but the generated packs are incompatible with
+versions of git older than (and including) v1.4.3; do not set
+the variable in a repository that older version of git needs to
+be able to read (this includes repositories from which packs can
+be copied out over http or rsync, and people who obtained packs
+that way can try to use older git with it).
 
 
 Author