In the following lines:
$ git tag -n1
v1.8 Tagged the day before yesterday
v1.9 Tagged yesterday
v2.0 Tagged today
$ git describe
v1.9-5
Most likely from your example, v1.9
is a tag from merge commit.
It is expected git behavior by default and you can read more about it here: https://git.kernel.org/pub/scm/git/git.git/commit/?id=80dbae03
To ignore merge tags when looking for most recent on the current branch you can use --first-parent
option.
git describe --tags --first-parent --abbrev=0
--first-parent
Follow only the first parent commit upon seeing a merge commit. This is useful when you wish to not match tags on branches merged in the history of the target commit.
Ref: https://git-scm.com/docs/git-describe