An error message would be printed at each update_depot_tools invocation.

TBR=mhm
BUG=none
TEST=running gclient shouldn't print an error message at each invocation anymore

Review URL: http://codereview.chromium.org/6690008

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@78021 0039d316-1c4b-4281-b951-d872f2087c98