make setup.py import setuptools if it sees bdist_egg in sys.argv

setup.py

@@ -17,7 +17,10 @@ import re
 import traceback
 import glob
 from distutils.command import build_ext
-from distutils.core import Extension, setup
+if 'bdist_egg' in sys.argv:
+    from setuptools import Extension, setup
+else:
+    from distutils.core import Extension, setup
 from os.path import join, isdir, abspath, basename, exists
 
 __version__ = re.search("__version__\s*=\s*'(.*)'", open('gevent/__init__.py').read(), re.M).group(1)