Re: Git makes a merge commit but as a normal (non-merge) commit

From: Michael J Gruber <git@grubix.eu>
Date: Aug 21, 2017, 10:03 UTC
Message-ID: <d5bc0c8b-900f-456b-55a9-35408187d06c@grubix.eu>
In-Reply-To: <CAM_JFCzZWfyUiFVrYOztdJD8iSYvYUavbzKOX2bxDV0_hMz7Eg@mail.gmail.com>

hIpPy venit, vidit, dixit 19.08.2017 00:35:

Show 32 quoted lines

> While merging if I do certain actions then the merge commit is made
> with the merge message but as a normal (non-merge) commit.
> 
> Repro steps:
> - Set GIT_MERGE_AUTOEDIT=yes (set other than "no") in .bashrc
> - Make a merge commit with no conflicts.
>   (external text editor shows the generated merge message)
> - Focus on Git Bash and Ctrl-C.
> - Commit (git commit).
> 
> Actual behavior:
> Git makes a normal (non-merge) commit (squash merge) but with the
> merge commit message.
> 
> It looks like a bug to me. This is very confusing later on as the repo
> topology would show that the branch is not merged in and there is not
> an easy way to find out when the merge was made.
> 
> Expected behavior:
> Git should stay in a MERGING state. The user can choose to either
> abort the merge or continue the merge (git merge --continue OR git
> commit).
> 
> This does not happen in case of conflicts (at least I'm not able to
> repro). I get a (master|MERGING) prompt till I resolve the conflicts
> and commit, which goes through correctly as a merge commit.
> 
> Environment:
> $ git version
> git version 2.14.0.windows.2
> $ bash --version
> GNU bash, version 4.4.12(1)-release (x86_64-pc-msys)

Thanks for the detailed info!

It turns out that his is not Windows specific. The recipe is:
- make "git merge" call and wait for an editor
- kill "git merge" while it waits for the editor

The effect is that prepare_to_commit() has no chance to call abort_commit() any more (which would call write_merge_state())..

Now, I'm not sure why we only do half of write_merge_state() (write out the merge_msg, but not merge_head) before launching the editor.

In any case, the following patch solves the problem and passes the existing tests. But I'll wait for more comments (and think about a test meanwhile).

Michael