Now that we clone "main" by default, use that for our local test.
Change-Id: Ib8420074bdfabfcb9d5252a3a0ecd3d852ca36e8
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/288422
Reviewed-by: Jonathan Nieder <jrn@google.com>
Tested-by: Mike Frysinger <vapier@google.com>