To download the current development version of bash-completion, you need to clone a git copy.
If you just want a read-only copy:
$ git clone git://git.debian.org/git/bash-completion/bash-completion.git
If you have an Alioth account, with write access to the bash-completion project, use this command:
$ git clone git+ssh://<username>@git.debian.org/git/bash-completion/bash-completion.git
Here username is your full Alioth username. It will have a -guest suffix if you're not a Debian Developer. See Alioth/SSH for more info.
Development on 1.x
If you want to checkout origin/1.x in a local branch 1.x, use these commands:
$ git pull origin
$ git checkout --track -b 1.x origin/1.x
Now both git pull and git push will work from/to origin/1.x.
If you choose a different name <nick> for the local branch, git push needs the refspec argument, because git push by default only compares local branch names with remote branch names:
$ git push origin <nick>:1.x
You can put this in .git/config for later pushes with this command:
$ git config remote.origin.push <nick>:1.x
What to commit?
Please only commit important bugfixes needed to be addressed in new minor releases (i.e. 1.1, 1.2, 1.3 and so on for the 1.x branch). NEVER EVER INTRODUCE NEW FEATURES OR RADICAL CHANGES.
Old frozen/1.0 branch
Please don't use it anymore, instead commit only to the 1.x branch.