I have been using bzr for all of my importlib work. It's worked out well sans the problem that SOMEONE <cough>Barry</cough> has not upgraded the bzr installation to support the newest wire protocol.
I'm probably to blame for this. Debian doesn't come with the latest bzr revision (bzr evolves way too fast for Debian, so that even their backports infrastructure doesn't provide recent binaries). I'm fairly opposed to installing non-vendor packages on www.python.org, as those typically don't see any maintenance, and often break as the regular packages get upgraded.
As a consequence, I would always request that whatever VCS Python uses: the version that is in the current Debian's "stable" distribution must be sufficient to use the VCS, and must in particular be sufficient on the server side.
Unfortunately, the current Debian release is stuck in political debates, so that we still can't use subversion 1.5 on the server.