Clear UserData in prpy.Clone (fixes #111 and #114)

Author: Michael Koval

src/prpy/clone.py

@@ -83,6 +83,11 @@ def __init__(self, parent_env, clone_env=None, destroy_on_exit=None,
 
         # Actually clone.
         with self.clone_env:
+            # Clear user-data. Otherwise, cloning into into the same target
+            # environment multiple times may not cause CloneBindings to get
+            # called again.
+            self.clone_env.SetUserData(None)
+
             if self.clone_env != self.clone_parent:
                 with self.clone_parent:
                     self.clone_env.Clone(self.clone_parent, self.options)