the behavior before I started messing with it. It turns out it's not worth the
hassle to try and "clean this up"; we depend on the current convoluted
semantics, which is to crawl up the tree from the current dir looking for
codereview.settings files, but to only ever look for PRESUBMIT.py in the
root of the repo. Trying to unify the logic seems to be too painful.

   BUG=none
   R=maruel@chromium.org
   TEST=none

Review URL: http://codereview.chromium.org/387067

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@33648 0039d316-1c4b-4281-b951-d872f2087c98