Support sshkey in merger.

The gerrit trigger took an sshkey parameter, but the merger,
which uses GitPython, did not honor it.  Add a GIT_SSH wrapper
for the merger to use to support arbitrary ssh keys for remote
git operation.

Change-Id: I43f0830905ee7103a2acbfa4b4f90959254f60b2
Reviewed-on: https://review.openstack.org/17269
Reviewed-by: Jeremy Stanley <fungi@yuggoth.org>
Reviewed-by: Paul Belanger <paul.belanger@polybeacon.com>
Reviewed-by: Clark Boylan <clark.boylan@gmail.com>
Approved: James E. Blair <corvus@inaugust.com>
Tested-by: Jenkins
2 files changed