Destination Host of VM during migration now notify Source host of exact socket path

ucloud/common/request.py

@@ -19,6 +19,7 @@ class RequestType:
 class RequestEntry(SpecificEtcdEntryBase):
 
     def __init__(self, e):
+        self.destination_sock_path = None
         self.destination_host_key = None
         self.type = None  # type: str
         self.migration = None  # type: bool