Re: Bug: git-describe abbrev documentation mentions wrong default

> The documentation for the "git describe --abbrev" flag says that the
> default value is 7 hexadecimal digits:
> https://github.com/git/git/blob/master/Documentation/git-describe.txt#L63
> and
> https://git-scm.com/docs/git-describe
>
> I have experienced that sometimes I see 7 digits, but other times more.
> The behavior seems to have changed in git 2.11.0 ("default abbreviation
> length"):
> https://github.com/git/git/blob/aeddbfdfa48443c034a9b28b10dfddf2f71b907f/Documentation/RelNotes/2.11.0.txt
>
> I was able to trigger different behavior using a bash script like the one
> below:
>
> ```sh
> #!/bin/bash
>
> DIR=test-git-describe
> rm -rf ${DIR}
> mkdir ${DIR}
> cd ${DIR}
> git init
>
> # One-time test results I have seen:
> # 10 tags, 10 * 10 commits: 7 hex digits
> # 100 tags, 100 * 100 commits: 8 hex digits
> FILE=foo
> touch ${FILE}
> for i in `seq 1 10`; do
>     echo ${i} >> ${FILE}
>     git add ${FILE}
>     git commit -m "Tag update number ${i} to ${FILE}"
>     git tag -m "Version 1.0.${i}" -a 1.0.${i}
>     for j in `seq 1 10`; do
>         echo ${i}-${j} >> ${FILE}
>         git add ${FILE}
>         git commit -m "Update number ${i}-${j} to ${FILE}"
>     done
> done
> ```