Re: [PATCH 2/2] name-rev: favor describing with tags and use committer date to tiebreak

From: Junio C Hamano <gitster@pobox.com>
Date: Mar 17, 2017, 05:56 UTC
Message-ID: <xmqqshmc8n09.fsf@gitster.mtv.corp.google.com>
In-Reply-To: <xmqqy3w48nif.fsf@gitster.mtv.corp.google.com>

Junio C Hamano <gitster@pobox.com> writes:

Show 13 quoted lines

> Lars Schneider <larsxschneider@gmail.com> writes:
>
>> A quick bisect indicates that this patch might break 
>> t9807-git-p4-submit.sh 8 and 13. I haven't looked into
>> it further, yet.
>
> As I do not do P4, help in diagnosing why it breaks is appreciated.
> If the test script expects...
> On the other hand, if git-p4 command internally uses name-rev and it
> is not prepared to properly handle commits that can be named in more
> than one way, the problem would be deeper, as it would mean it can
> misbehave even without the change to name-rev when multiple branches
> point at the same commit.

Yikes.  Perhaps something along this line?

This function seems to want to learn which branch we are on, and running "name-rev HEAD" is *NEVER* the right way to do so. If you are on branch B which happens to point at the same commit as branch A, "name-rev HEAD" can say either A or B (and it is likely it would say A simply because it sorts earlier, and the logic seems to favor the one that was discovered earlier when all else being equal).

 git-p4.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/git-p4.py b/git-p4.py
index eab319d76e..351d1ab58e 100755
--- a/git-p4.py
+++ b/git-p4.py
@@ -582,7 +582,7 @@ def currentGitBranch():
         # on a detached head
         return None
     else:
-        return read_pipe(["git", "name-rev", "HEAD"]).split(" ")[1].strip()
+        return read_pipe(["git", "symbolic-ref", "HEAD"]).strip()[11:]
 
 def isValidGitDir(path):
     return git_dir(path) != None