gclient revinfo alone will now not return the actual checked out revisions but simply what's in the .gclient&DEPS.

BUG=none
TEST=add a --snapshot test to make sure it is not broken

Review URL: http://codereview.chromium.org/3130007

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@55760 0039d316-1c4b-4281-b951-d872f2087c98