use git clone --branch instead of --no-checkout

git submodule update does not cause an actual checkout if HEAD matches
the recorded submodule sha1 even if it was not actually checked out.

it would be possible to work around this by calling git checkout HEAD in
each submodule if no files are checked out, but that seems hacky.

instead, just make the module cloning already check out the desired
branch. this produces checkouts that are within a few commits of the
final sha1, so isn't too bad.

Change-Id: I435c1a2e24f39fd8c0d65f0d90df0216715668b7

0 files changed, 0 insertions, 0 deletions