bpo-11572: Make minor improvements to copy module (GH-8208)

* When doing getattr lookups with a default of "None", it now
  uses an "is" comparison against None which is more correct
* Removed outdated code

Patch by Brandon Rhodes.

Lib/pickle.py

@@ -510,11 +510,7 @@ class _Pickler:
             rv = reduce(obj)
         else:
             # Check for a class with a custom metaclass; treat as regular class
-            try:
-                issc = issubclass(t, type)
-            except TypeError: # t is not a class (old Boost; see SF #502085)
-                issc = False
-            if issc:
+            if issubclass(t, type):
                 self.save_global(obj)
                 return