support --first-parent option in the jgit implementation of "git describe"

[helterscelter]

the current jgit based implementation doesn't have an option to choose tags by following the --first-parent. This is supposed to allow you to skip tags which are introduced by merges into the current branch. think multi-branch repositories where master/trunk represents "production". if you merge a hotfix forward from "master" into one of your develop branches, the annotated tag from the hotfix will be picked up instead of the tag on the development line.

[TheSnoozer]

Hi @helterscelter
thaks for reporting this here. This sounds like a great idea to go for.
You got the point that it mostly needs some jgit-implementation adjustments...
Ideas and PRs are very welcome :-)

[TheSnoozer]

see: https://stackoverflow.com/questions/33038224/how-to-call-git-show-first-parent-in-jgit

[michalrrcc]

When having multiple long lived branches this option would be very useful, otherwise tags need to be moved manually after every merge.