The major use case was for ChromiumOS devs who were using repo. It's not a
frequent use case anymore. Having git-cl sync on each invocation is costly.

TBR=nsylvain@chromium.org
BUG=
TEST=


Review URL: http://codereview.chromium.org/9389030

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@121834 0039d316-1c4b-4281-b951-d872f2087c98