pylint checks were erronously excluded for PRESUBMIT.py files in
root directory of repos because the regex was getting a './' added.

R=iannucci@chromium.org
TBR=M-A

Review URL: https://chromiumcodereview.appspot.com/11880040

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@176777 0039d316-1c4b-4281-b951-d872f2087c98