Find the next tag on a given branch

Dear list,

I want to find the next tag (the tag following a commit), but require that it lie on a given branch. Alternatively, a filter pattern might work too.

My challenge is to answer the question:

  "Which is the first Debian release including a given commit"

The way Debian packages are (mostly) maintained in Git is that there are at least an upstream and a Debian branch (usually "master"). master branched off upstream, and upstream is merged into master at regular intervals. Whenever a Debian release is made, the corresponding branch is tagged.

If I run

  git describe --contains mycommitish

it prints the next tag, which is usually upstream's tag, which is not quite what I want (it's usually enough for me to figure it out, but this is Git and so I should be able to do even better! ;\) )

I would like to have it continue the search until it reaches the master branch. For instance, a command like

  git describe --contains mycommit --on-branch master

would basically search into the future (breadth-first?) until it landed on the specified branch, and then continue the normal search routine (and find the commit on another branch actually, the important point is that it only started to search for tags once it reached the specified branch).

The alternative is

  git describe --contains mycommit --pattern='debian/*'

which would keep searching for tags until it found a tag/ref-name that matched the specified glob.

Is this already possible somehow? Am I simply looking at the wrong tools?

Thanks,