I just realixed... there is a way to download the bugs from savannah. Additionally there is an API for interfacing with the bug system on github. The various ids (for groups or subprojects... gui, base, etc) can be discovered easily.
If this is something we would like to do, then I can write the script to do the transition. I may try an initial run on gorm's repo just to test it out.
This would not necessarily mean shutting down the bug tracker at savannah... we would just need to keep them in sync.