Some of our older branches have large git repositories which are no longer present in ChromeOS. Initial sync times for branch builds can be improved substantially by having these git repos included in the preload.

If there is an existing checkout in place, other branches can be checked out with:

repo init --manifest-branch "branchname"
repo sync --network-only

Then, to switch back to master when finished:

repo init --manifest-branch master
repo sync --local-only