Don't unlock VMs when destroy fails

Signed-off-by: Zack Cerza <zack@redhat.com>

teuthology/lock/ops.py

@@ -163,6 +163,7 @@ def unlock_one(ctx, name, user, description=None):
     name = misc.canonicalize_hostname(name, user=None)
     if not teuthology.provision.destroy_if_vm(ctx, name, user, description):
         log.error('destroy failed for %s', name)
+        return False
     request = dict(name=name, locked=False, locked_by=user,
                    description=description)
     uri = os.path.join(config.lock_server, 'nodes', name, 'lock', '')