aptitude development moves to Mercurial, back to Alioth
Short version: the aptitude development tree is now maintained using Mercurial, go here to fetch it.
aptitude development has been using darcs as a version control system for the last two years. Darcs is a distributed version control system with many great concepts -- but it has one huge, glaring, enormous flaw, which is that innocuous operations, like merging one branch into another, can require practically unbounded amounts of time and space. And once two branches get screwed up in this way, there is nothing, nothing at all, that you can do to get yourself unwedged; the cause is a design flaw in darcs that no-one seems to know how to fix or work around.
Recently, I made the mistake of changing some files in both the Debian branch of aptitude and the head branch, and when I tried to merge the two branches to upload a new upstream release, darcs went off into la-la land. So, I figured that it was probably time to switch version control systems.
I'd like to say that I did extensive research on the matter, but the truth is that I chose Mercurial based on the fact that (A) a lot of ex-darcs users have written nice things about it, (B) git and arch-derived systems always feel ugly to me, and (C) John Goerzen implemented support for mercurial on Alioth. Yes, I am so a follower.
So if you want the up-to-date aptitude source, you should go to http://hg.debian.org/hg/aptitude/head. You can also fetch an RSS feed from http://hg.debian.org/hg/aptitude/head?style=rss.
You can fetch a copy of the repository with "hg clone http://hg.debian.org/hg/aptitude/head aptitude-head". To update, I recommend putting the following lines in ~/.hgrc to enable the "fetch" extension:
Once you've done this, just run "hg fetch" and it should download and merge the latest code. You may want to install kdiff3 to get a better merge tool as well.
To commit a patch locally, run "hg commit". Unfortunately, there doesn't seem to be any easy way for people to send patches back within the VCS like there is for darcs (one of many nice features I had to give up in favor of being able to actually get work done -- what, me bitter?), but it looks like you can get somewhere with "hg bundle <file>", then mailing the resulting file off.