[autotest] Allows us to pull repos as part of build_externals.
Pulls/clones chromite and hdctools/servo into site-packages. Also add
helper methods to revision_control.py and a -work-tree option, along
with a unittest.
TEST=built externals and imported servo/chromite.
BUG=chromium-os:38096
Change-Id: I1bae6e3f730495030665267876c8594800aa27d4
Reviewed-on: https://gerrit.chromium.org/gerrit/41910
Commit-Queue: Prashanth Balasubramanian <beeps@chromium.org>
Reviewed-by: Prashanth Balasubramanian <beeps@chromium.org>
Tested-by: Prashanth Balasubramanian <beeps@chromium.org>
3 files changed