issue #106: has_parent_authority should accept own context ID.

When a stream (such as unix.connect()) has its auth_id set to the
current context's, we should allow those requests too, since the request
is working with the privilege of the current context.

mitogen/core.py

@@ -157,8 +157,9 @@ def _unpickle_dead():
 _DEAD = Dead()
 
 
-def has_parent_authority(msg, _stream):
-    return msg.auth_id in mitogen.parent_ids
+def has_parent_authority(msg, _stream=None):
+    return (msg.auth_id == mitogen.context_id or
+            msg.auth_id in mitogen.parent_ids)
 
 
 def listen(obj, name, func):