Write a script automating branches cleanup

Each feature or fix generates a new branch. A cleanup is needed.

IMHO, this should not be automated in the testandpush jobs (make them delete the branch after merge):
<< It's too short in time. Branches are often useful for later review (especially when merge conflicts were resolved). At the difference of the rebase action, the merge is potentially destructive and looses some informations (although we want/need a merge on master, not a rebase).

Alternatively, I would suggest a script locating "merged" branches older than 3 or 6 months.
The script would either produce a list of branches to delete, for review, either automatically delete them (in which case it would notify by email the branches name and hash being deleted).
Unmerged branches must be manually removed by their authors once they are useless. The script could warn about such branches which were not updated for a while. >>

Note also that local branches removed from the remote are deleted by the following command (included in "git in" alias): git remote update -p.