Mercurial
This explains how to stay up to date with your sources using mercurial (a.k. hg). The repo on ftp.fortunaty.net is used, which replicates corecode's (http://chlamydia.fs.ei.tum.de/hg/dragonfly-src) hourly.
Install mercurial
cd /usr/pkgsrc/devel/mercurial && bmake install
If you need only one source tree around
cd /usr
hg clone http://ftp.fortunaty.net/DragonFly/dragonfly-src.hg src
Later you update with
cd /usr/src && hg pull -u
If you need more than one, maybe for developement
hg clone -U http://ftp.fortunaty.net/DragonFly/dragonfly-src.hg /home/dsrc.hg
hg clone /home/dsrc.hg /usr/src
Later you update your local master repo with
cd /home/dsrc.hg
hg pull
Then your slave trees
cd /usr/src
hg pull -u