git_cl: fix GetPreferredTryMasters() feature
git_cl: fix GetPreferredTryMasters() feature

It was broken in https://chromiumcodereview.appspot.com/2419113002

R=borenet@chromium.org
BUG=658317

Review-Url: https://codereview.chromium.org/2442393002

CoherentLabs/depot_tools,CoherentLabs/depot_tools