git push/pull doesn't touch references outside of branches and git-bug has special code in the push/pull commands to merge bugs when needed.
How does that work with garbage collection?
As each bug reference the file blob needed, once your delete a bug, `git gc` will clean these blob as well.
The question isn't whether the data will be garbage collected, but how the active data AVOIDS being garbage collected - git gc only targets a pretty small amount of refs to preserve.
I'd be fine running a patched git that knows about bugs. Of course, then I'd want to make it a little more generic, and not care whether I was dealing with an issue tracker, a wiki, etc.