Fix missing space in exception message
Fix missing space in exception message

Change-Id: I950fe126da843e6f3158b5f2fd12b4ce213947e8

ChameleonCloud/horizon,ChameleonCloud/horizon,yeming233/horizon,NeCTAR-RC/horizon,noironetworks/horizon,noironetworks/horizon,yeming233/horizon,yeming233/horizon,NeCTAR-RC/horizon,BiznetGIO/horizon,openstack/horizon,openstack/horizon,openstack/horizon,NeCTAR-RC/horizon,ChameleonCloud/horizon,noironetworks/horizon,BiznetGIO/horizon,noironetworks/horizon,openstack/horizon,yeming233/horizon,NeCTAR-RC/horizon,BiznetGIO/horizon,ChameleonCloud/horizon,BiznetGIO/horizon