The broken PRESUBMIT.py was fixed so reintegrating revision 17554 (which was good in the first place).

BUG=none
TEST=none
TBR=joi
Review URL: http://codereview.chromium.org/119130

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@17578 0039d316-1c4b-4281-b951-d872f2087c98