Some external contributors need their CL's try'd quickly, but currently its not easy unless we patch locally. This will allow you to submit the rietveld issue number and will do the rest automatically. As well, renable the dry_run option. It was removed. 

BUG=None 
TEST=git try --issue 12345
Review URL: http://codereview.chromium.org/481006

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@35881 0039d316-1c4b-4281-b951-d872f2087c98