The repo server role was updated to allow serving repositories over the
git protocol in I62321a7b62dabca469eb072ddbf4e8f250ce0fb3.
Update the git tasks checking out the tempest repository to automatically
accept host keys so that the git procotol can become the default in the
integrated openstack-ansible deployment.
Change-Id: I9e949080f7f23f027fe7125137e86d3041b24df5
Signed-off-by: Kevin Carter <kevin.carter@rackspace.com>