Undo the change to `disco.util.config.Config`.

There is probably a way to do this, but that's topic of a different PR.

disco/util/config.py

@@ -8,7 +8,7 @@ from .serializer import Serializer
 class Config(object):
     def __init__(self, obj=None):
         self.__dict__.update({
-            k: copy.deepcopy(getattr(self, k)) for k in dir(self.__class__)
+            k: getattr(self, k) for k in dir(self.__class__)
         })
 
         if obj: