bug in 'git describe'?

From: Sebastian Kuzminsky <seb@highlab.com>
Date: Sep 24, 2018, 21:45 UTC
Message-ID: <fd340f7b-61c0-2661-bdca-c239e51bc464@highlab.com>

I think I've run in to a bug in 'git describe' (reproduced with git 2.11.0, 2.16.1, and 2.19.0.221.g150f307af).

I've got two tiny git repos whose commit graphs are identical, but where 'git describe' gives different results.

Show 16 quoted lines

>     *   merge 1.1 into 2.0  (HEAD -> release-2.0)
>     |\
>     | *   merge boo into 1.1  (tag: release/1.1.1, release-1.1)
>     | |\
>     | | * dummy commit  (boo)
>     | * | dummy commit  (tag: release/1.1.0)
>     * | |   merge feature into 2.0
>     |\ \ \
>     | * | | dummy commit  (feature)
>     |/ / /
>     * | | dummy commit  (tag: release/2.0.1)
>     * | | dummy commit  (tag: release/2.0.0)
>     |/ /
>     * | dummy commit  (release-1.0)
>     |/
>     * dummy commit  (tag: release/1.0.0)

The tag 'release/1.0.0' is the first commit in history.

The histories differ only in the timestamps of the commits (and thus the SHAs of the commit objects).

Good repo: release/2.0.1-6-gbc33a04 Bad repo: release/2.0.1-8-g2c0a20c

Details, including full copies of both repos, here:

http://highlab.com/~seb/git-describe-bug/

-- 
Sebastian Kuzminsky