Do not force using the remote "origin" when testing upgrades
Do not force using the remote "origin" when testing upgrades

Zuul checkout of origin/stable/pike doesn't work, and needs
only stable/pike instead [1].

[1]: http://logs.openstack.org/periodic/git.openstack.org/openstack/openstack-ansible/master/openstack-ansible-upgrade-ceph-ubuntu-xenial/f835b74/job-output.txt.gz#_2017-11-24_06_08_06_547867

Change-Id: Ib2bee665e164f02817487c311e125329d54c43d8

openstack/openstack-ansible,stackforge/os-ansible-deployment,openstack/openstack-ansible,stackforge/os-ansible-deployment,bunchc/openstack-ansible,bunchc/openstack-ansible,cfarquhar/openstack-ansible,cfarquhar/openstack-ansible