set()/frozenset() also return their own instance

Cython/Compiler/Builtin.py

@@ -124,9 +124,8 @@ types_that_construct_their_instance = (
     # some builtin types do not always return an instance of
     # themselves - these do:
     'type', 'bool', 'long', 'float', 'bytes', 'unicode', 'tuple', 'list',
-    'dict', 'file',
+    'dict', 'file', 'set', 'frozenset'
     # 'str',             # only in Py3.x
-    # 'set', 'frozenset' # only in Py2.4+
     )