true. and actually bup can't use git's tooling directly because of the different use cases it's optimized for. git won't make any use of bup's optimizations: midx (combination of multiple .idx files into a handful of bigger ones to reduce page faults during binary searches) and bloom filter.

git's tools, namely filter-branch and gc have been reported to work on limited-size bup repositories, but it very quickly eats up all ram and cpu and never finishes because of the sheer amount of objects that are usually stored in a bup repository