After changing this to '%f%' instead of just '%' this doesn't
work anymore. It should be '%f%%' instead.

BUG=
TBR=iannucci@chromium.org

Review URL: https://codereview.chromium.org/1156023008

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@295539 0039d316-1c4b-4281-b951-d872f2087c98