pylint is useful to catch errors before they go live so fix little annoyances.

BUG=none
TEST=none

Review URL: http://codereview.chromium.org/3372001

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@58817 0039d316-1c4b-4281-b951-d872f2087c98