Revert integrator deepcopy

wrappers/python/src/swig_doxygen/swig_lib/python/extend.i

@@ -454,6 +454,7 @@ Parameters:
         copy = self.__class__.__new__(self.__class__)
         copy.__init__(self)
         return copy
+
     def __deepcopy__(self, memo):
         return self.__copy__()
   %}
@@ -469,11 +470,12 @@ Parameters:
         system = XmlSerializer.deserialize(serializationString)
         self.this = system.this
 
+    def __copy__(self):
+        copy = self.__class__.__new__(self.__class__)
+        copy.__init__(self)
+        return copy
+
     def __deepcopy__(self, memo):
         return self.__copy__()
   %}
-  %newobject __copy__;
-  OpenMM::Integrator* __copy__() {
-      return OpenMM::XmlSerializer::clone<OpenMM::Integrator>(*self);
-  }
 }