[setup] do not call parent function via super, because Extension is a…

…n old-style class.

basesetup.py

@@ -5,8 +5,8 @@
 import shutil
 import subprocess
 import tempfile
+from setuptools import Extension
 from distutils.dep_util import newer_group
-from distutils.core import Extension
 from distutils.errors import DistutilsExecError, DistutilsSetupError
 from distutils.ccompiler import new_compiler
 from distutils.sysconfig import customize_compiler, get_config_vars
@@ -264,7 +264,7 @@ def build_extension(self, ext):
     def copy_extensions_to_source(self):
         _extensions = self.extensions
         self.extensions = [e for e in _extensions if not isinstance(e, StaticLibrary)]
-        super(build_ext, self).copy_extensions_to_source()
+        _build_ext.copy_extensions_to_source(self)
         self.extensions = _extensions
 
     def build_static_extension(self, ext):