I've get in touch with Guido and explained him some missing things I had found on git-dch (part of git-buildpackage). The most amazing thing is that he implemented them all and his code is much nicer then mine since it has been wrote using the Python extensions for the GIT.

Please, migrate your scripts that use git-update-debian-change (if there's someone else then me using it) to use git-dch since I'll drop it next week.