Possible bug in git describe, additional commits differs when cloned with --depth

Hi,

I'm not sure if this is a bug or not but `git describe` gives different results when the repo has been cloned with `--depth` or not.

In the example below from the git repository the number of additional commits since the last tag differs 256 vs. 265.

``` $ git clone https://github.com/git/git $ cd git/ $ git describe v2.23.0-256-g4c86140027 $ git rev-list -n 1 HEAD 4c86140027f4a0d2caaa3ab4bd8bfc5ce3c11c8a

$ git clone --depth=50 https://github.com/git/git git-depth $ cd git-depth/ $ git describe v2.23.0-265-g4c861400 $ git rev-list -n 1 HEAD 4c86140027f4a0d2caaa3ab4bd8bfc5ce3c11c8a ```

In the example above the first version also gives additional digits for the SHA, g4c86140027 vs. g4c861400, but that is not always the case.

I came upon this discrepancy when using the value from `git describe` in a build pipeline where the system optimized the build by cloning the repo using `--depth`.

Kind regards -- http://anders.janmyr.com/ @andersjanmyr +46 733-99 03 60