Ubuntu contributions are managed via the launchpad platform. Once you subscribe you can contribute checking out projects with bzr.
Ubuntu comes with a bzr “launchpad” plugin. You can register your ssh public key here
then join with:
#bzr launchpad-login user
Checkout your source project – eg u1ftp, the ubuntu one ftp gateway.
#bzr branch lp:u1ftp u1ftp-origin
Do your patch, commit and then push it!
bzr push lp:~rpolli/u1ftp/unicode_support