We follow the GitFlow model and we've ended up with a lot of obsolete feature branches on our server due to people not selecting to delete feature branches after pull requests for a number of reasons (usually reticence).

We can manually clean up these branches by setting the default branch as develop and finding and deleting any which aren't ahead of the develop branch, but this is currently tricky when there are a lot of active feature branches present.

The easy solution would be to add a filter to the Branches view that allows showing only those branches that are not ahead of the default branch. Then there could also be a 'Delete All' button activated if this was enabled to delete all the branches en masse.