Don't deepcopy RpcContext

Instead of deepcopying the RpcContext, which seems to not work
sometimes, we'll explicitly create a new instance of the class and
deepcopy the required values.

Fixes bug 1007043

Change-Id: I6578c4c82046acf149724a1c5985fa6b46857a7c

nova/rpc/amqp.py

@@ -175,6 +175,12 @@ def __init__(self, **kwargs):
         self.conf = kwargs.pop('conf')
         super(RpcContext, self).__init__(**kwargs)
 
+    def deepcopy(self):
+        values = self.to_dict()
+        values['conf'] = self.conf
+        values['msg_id'] = self.msg_id
+        return self.__class__(**values)
+
     def reply(self, reply=None, failure=None, ending=False,
               connection_pool=None):
         if self.msg_id:

nova/rpc/common.py

@@ -287,6 +287,9 @@ def to_dict(self):
     def from_dict(cls, values):
         return cls(**values)
 
+    def deepcopy(self):
+        return self.from_dict(self.to_dict())
+
     def update_store(self):
         local.store.context = self
 
@@ -299,7 +302,7 @@ def elevated(self, read_deleted=None, overwrite=False):
         # convert the RpcContext back to its native RequestContext doing
         # something like nova.context.RequestContext.from_dict(ctxt.to_dict())
 
-        context = copy.deepcopy(self)
+        context = self.deepcopy()
         context.values['is_admin'] = True
 
         context.values.setdefault('roles', [])

nova/rpc/impl_fake.py

@@ -34,6 +34,13 @@ def __init__(self, **kwargs):
         self._response = []
         self._done = False
 
+    def deepcopy(self):
+        values = self.to_dict()
+        new_inst = self.__class__(**values)
+        new_inst._response = self._response
+        new_inst._done = self._done
+        return new_inst
+
     def reply(self, reply=None, failure=None, ending=False):
         if ending:
             self._done = True