Re: [BUG?] git checkout -b removes MERGE_HEAD

From: Junio C Hamano <gitster@pobox.com>
Date: Nov 18, 2010, 18:39 UTC
Message-ID: <7vwroabhng.fsf@alter.siamese.dyndns.org>
In-Reply-To: <456aec650e66bba518b8a5ec88c88a6b.squirrel@artax.karlin.mff.cuni.cz>

"Jan Hudec" <bulb@ucw.cz> writes:

Show 11 quoted lines

>  - During the testing I found a problem, but it may have already
>    existed on master before the merge.
>  - Therefore I needed to return to clean master, test it and return
>    to the merge. So I thought I'd commit the merge to a temporary
>    branch, test master again and merge the temporary to master if
>    the problem is not from the merge. So I did:
>
>    $ git checkout -b temp
>    $ git commit
>
>    OOPS! It forgot it was a merge.

I think it was an oversight by the author of 91dcdfd (Make "git checkout" create new branches on demand, 2005-07-11) who forgot that he also did ef0bfa2 (Remove MERGE_HEAD in "git checkout/reset", 2005-06-21). The rationale for the removal of MERGE_HEAD from the earlier commit is:

    [this command] will end up resetting the index to some specific
    head, and any unresolved merge will be forgotten [hence there is no
    point recording the result as a merge].

but when used with -b no such "resetting of the index" happens.

Having said that, changing it not to remove MERGE_HEAD and MERGE_MSG is probably not sufficient, as MERGE_MSG would likely to already record to which branch you are recording the merge (I didn't check, though).