Fix bug in serverprovider.test_openstack_provider
Fix bug in serverprovider.test_openstack_provider

OpenStackProviderTestCase.test_openstack_provider_create_vms was fixed
by correct mocking.

Change-Id: I78810dacdc6f18d808926a0f984d98c4b663d158
Closes-Bug: #1259249

vganapath/rally,go-bears/rally,eayunstack/rally,vefimova/rally,eonpatapon/rally,yeming233/rally,openstack/rally,aforalee/RRally,aplanas/rally,vponomaryov/rally,eonpatapon/rally,gluke77/rally,go-bears/rally,paboldin/rally,group-policy/rally,paboldin/rally,ytsarev/rally,ytsarev/rally,gluke77/rally,varunarya10/rally,eayunstack/rally,redhat-openstack/rally,aforalee/RRally,openstack/rally,vganapath/rally,pandeyop/rally,vganapath/rally,pandeyop/rally,openstack/rally,vefimova/rally,gluke77/rally,yeming233/rally,vganapath/rally,eayunstack/rally,amit0701/rally,openstack/rally,shdowofdeath/rally,gluke77/rally,paboldin/rally,amit0701/rally,aplanas/rally,redhat-openstack/rally,pyKun/rally,cernops/rally,cernops/rally,group-policy/rally,shdowofdeath/rally,afaheem88/rally,afaheem88/rally,group-policy/rally,varunarya10/rally,vponomaryov/rally,pyKun/rally,amit0701/rally