From: Andrew Wong <andrew.kw.w@gmail.com>
Date: Thu, 28 Apr 2011 04:35:55 +0000 (-0400)
Subject: git-rebase--interactive.sh: preserve-merges fails on merges created with no-ff
X-Git-Tag: v1.7.5.2~22^2
X-Git-Url: https://git.lorimer.id.au/gitweb.git/diff_plain/c192f9c865dbdae48c0400d717581d34cd315fb8?hp=c192f9c865dbdae48c0400d717581d34cd315fb8

git-rebase--interactive.sh: preserve-merges fails on merges created with no-ff

'git rebase' uses 'git merge' to preserve merges (-p).  This preserves
the original merge commit correctly, except when the original merge
commit was created by 'git merge --no-ff'.  In this case, 'git rebase'
will fail to preserve the merge, because during 'git rebase', 'git
merge' will simply fast-forward and skip the commit.  For example:

B
/ \
A---M
/
---o---O---P---Q

If we try to rebase M onto P, we lose the merge commit and this happens:

A---B
/
---o---O---P---Q

To correct this, we simply do a "no fast-forward" on all merge commits
when rebasing.  Since by the time we decided to do a 'git merge' inside
'git rebase', it means there was a merge originally, so 'git merge'
should always create a merge commit regardless of what the merge
branches look like. This way, when rebase M onto P from the above
example, we get:

B
/ \
A---M
/
---o---O---P---Q

Signed-off-by: Andrew Wong <andrew.kw.w@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---