The page detailing how to contribute a patch says:

When working on a patch, your local enlistment should in most cases be synchronized to the latest check-in in the contributions branch (contributions tip). Working on the dev branch would only expose you to nasty things (like the application breaking all the time).

However I can't find this branch. Which branch should I use to contribute a patch?

i think that is out of date,

now should use 1.x

Ok, thanks.