_check_output_svn sets the cwd to project_path
therefore files should not have project_path.

R=maruel@chromium.org,cmp@chromium.org
BUG=149702


Review URL: https://chromiumcodereview.appspot.com/10909254

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@156953 0039d316-1c4b-4281-b951-d872f2087c98