My old git-bugzilla integration scripts were more of a one-off attempt at some glue code and was very hackish. No wonder it accumulated bitrot.
So now, there's GitZilla! It's hosted on GitHub and there's a .deb available. Note that (for now at least), you would have to install the pybugz module separately, even if you install the GitZilla .deb.
Using GitZilla is extremely easy. You can get started by symlinking (or copying) a couple of files and creating a 4 line configuration file. (See the 'simple ready scripts' usage mode).