Clean up convergence error message
Clean up convergence error message

Cleans up the error message when acquiring a lock, adding some space and
making it more grep friendly.

Change-Id: I152a86f0f1040c3b7fefaf0bcc69eb0dd3353930

jasondunsmore/heat,dims/heat,noironetworks/heat,steveb/heat,gonzolino/heat,dragorosson/heat,jasondunsmore/heat,noironetworks/heat,steveb/heat,dragorosson/heat,cwolferh/heat-scratch,cwolferh/heat-scratch,openstack/heat,gonzolino/heat,openstack/heat,dims/heat