Enable git-cl-land for git-cache checkouts.
Enable git-cl-land for git-cache checkouts.

The key piece here is that when running 'git cl land' from a cache checkout, refs/pending/* must be fetched from / pushed to the cache mirror's remote.

BUG=589140
R=wkorman,agable,iannucci,martiniss

Review URL: https://codereview.chromium.org/1777693002

git-svn-id: fd409f4bdeea2bb50a5d34bb4d4bfc2046a5a3dd@299166 0039d316-1c4b-4281-b951-d872f2087c98

primiano/depot_tools,CoherentLabs/depot_tools,CoherentLabs/depot_tools,primiano/depot_tools,primiano/depot_tools