Add additional logging to flush selector

Adds additional debug logging to the flush selector to determine how any
why any given node is selected. Useful for troubleshooting strange
choices.

node-daemon/pvcnoded/fencing.py

@@ -88,7 +88,7 @@ def migrateFromFencedNode(zk_conn, node_name, config, logger):
     def fence_migrate_vm(dom_uuid):
         VMInstance.flush_locks(zk_conn, logger, dom_uuid)
 
-        target_node = common.findTargetNode(zk_conn, config, dom_uuid)
+        target_node = common.findTargetNode(zk_conn, config, logger, dom_uuid)
 
         if target_node is not None:
             logger.out('Migrating VM "{}" to node "{}"'.format(dom_uuid, target_node), state='i')