Disclaimer: I'm a member of the team working with Brett on the DVCS PEP, and definitely pro-DVCS (specifically working on the git parts).
"Martin v. Löwis" writes:
If "switching to a modern DVCS" means that users now need to start compiling their VCS before they can check out Python,
It doesn't mean that. All of the DVCS contenders have Windows and Mac OS installers (usually from 3rd parties, but working closely with the core). For *nix users, does anybody really use a vanilla Debian stable for a development workstation? Everybody else has reasonably fresh versions available via the standard package manager, even Debian Lenny.
I don't think we should switch to a modern DVCS. Such a system must be mature, and if it isn't included in Debian stable, it can't be mature (and free software).
The versions in Debian stable were all usable for their time, but this is a rapidly developing field, even when, like Subversion, your goal is to refactor software designed in the early 1990s! "It's in Debian stable" is an excessively strict standard for the client's version.
In the specific case, if a decision is made to switch to bazaar, and bzr 1.5 is recent enough, then I'd be happy to upgrade to testing (although 1.5 is also available from backports, and already installed; stable has bzr 0.11). Since lenny was frozen, bzr managed to release 5 minor versions (so it is 1.10 now); this makes me very worried whether this software is mature.
The bzr team is experimenting with a time-based release process; the rate at which minor versions appear should not worry you.
More important is the count of new repository formats. There are about 5 currently in common use. Great efforts are made to keep them interoperable, though some are not. Python should avoid use of those for the near future but I don't think it should be considered a showstopper.