Always use latest patchset in git-cl try
Always use latest patchset in git-cl try

Rietveld rejects tryjobs from non-latest patchsets anyway,
change logic to always use latest patchset.

R=iannucci@chromium.org

Review URL: https://chromiumcodereview.appspot.com/22415012

git-svn-id: bd64dd6fa6f3f0ed0c0666d1018379882b742947@216023 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

svn2github/chromium-depot-tools,svn2github/chromium-depot-tools,svn2github/chromium-depot-tools