Ignore errors when uninstalling a pkg with zypper
Ignore errors when uninstalling a pkg with zypper

I.e. when trying to uninstall python-pip and it's not installed,
don't exit.

Change-Id: I21ac715a0090ad01811af47f23c61823dfa65629

bswartz/devstack,Mahito/devstack,richliu/devstack,dtroyer/devstack,bswartz/devstack,richliu/devstack,samgoon/devstack,openstack-dev/devstack,noironetworks/devstack,bigswitch/devstack,nawawi/openstack,group-policy/devstack,samgoon/devstack,bigswitch/devstack,group-policy/devstack,nawawi/openstack,Mahito/devstack,openstack-dev/devstack,noironetworks/devstack,dtroyer/devstack