I hope #hggit pushes a working version out through pip soon. In the mean time, branch 1.3.x managed not to explode once. Afaict this has been another #python3 migration straggler. FYI, in my ~/.hgrc
hg-git = ~/clones/hg-git/hggit
and in the clone I had to
hg checkout -C 1.3.x
If you're not a #mercurial person, it "works great" as a #git client. With the above caveat.