Switching branches on Android Open Source Project

This is from Google Groups.
It is about switching between android branches easily.
------------------------------------------------------

You can re-run repo init on the same client, such that repo sync will
only re-download the new data.
repo init -b [branch]; repo sync

You can't just checkout in all projects, because (like I explained above):
-the list of projects changes from one branch to another, so the
notion of "all projects" can't be used to go across branches
-there's not a 1:1 mapping between names of manifests and names of
branches in individual projects.

As an extra trick, if you already have a client tracking one branch
and want a client tracking another branch:

create a new empty directory
run repo init in it (with the -u parameter)
copy the .repo/projects directory from your existing client into the new one.
repo sync

That'll only download the projects you don't already have.
JBQ