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.
Even if someone like me or Barry volunteers to maintain the installation of the DVCS software? I would be willing to do this if/when the replacement for svn is chosen.
Now we need to separate between server side and client side; for each side, there should be a minimum required version (which might be different).
If Debian stable doesn't include the minimum required client version, I will be opposed to switching to the DVCS.
If it doesn't include the minimum required server version, I could live with somebody maintaining a manual installation (which then hopefully can be replaced with an official package on the next upgrade).
This is why depending wholly on Debian for everything can be annoying. I understand the policy and support it overall, but in the case of something like a DVCS that doesn't have ridiculous dependencies like svn and someone explicitly taking the lead on the specific installation it would seem like an exception could potentially be made.
It's always possible to make exceptions. It's not just about the VCS; there have been requests to replace Apache, NTP, Zope, Postgres, MoinMoin, and a few other packages. There have been many problems on upgrade for the cases where we gave in: shared libraries were missing after the upgrade (for Zope), the software wasn't available anymore after the upgrade (in case of manually-install Python pacakges), and so on. Very few people have actually helped in fixing these problems (applause to AMK for being very helpful with the most recent incidents).
I'd rather have the users annoyed than finding out that the custom setup opened an entrance for hackers.