I guess it should be wrapped in a try, except:

try:
    from html.entities import name2codepoint
except ImportError:
    from htmlentitydefs import name2codepoint

This works locally

Here's a sample traceback:

Traceback (most recent call last):
  File "python2nix.py", line 119, in <module>
    egg_release = pypi.get_release(egg['name'] + '==' + version)
  File "/nix/var/nix/profiles/plone/lib/python2.7/site-packages/Distutils2-1.0a4-py2.7.egg/distutils2/pypi/simple.py", line 201, in get_release
    releases = self.get_releases(predicate, prefer_final)
  File "/nix/var/nix/profiles/plone/lib/python2.7/site-packages/Distutils2-1.0a4-py2.7.egg/distutils2/pypi/simple.py", line 189, in get_releases
    self._process_index_page(predicate.name)
  File "/nix/var/nix/profiles/plone/lib/python2.7/site-packages/Distutils2-1.0a4-py2.7.egg/distutils2/pypi/simple.py", line 75, in wrapped
    return func(self, *args, **kwargs)
  File "/nix/var/nix/profiles/plone/lib/python2.7/site-packages/Distutils2-1.0a4-py2.7.egg/distutils2/pypi/simple.py", line 397, in _process_index_page
    self._process_url(url, name)
  File "/nix/var/nix/profiles/plone/lib/python2.7/site-packages/Distutils2-1.0a4-py2.7.egg/distutils2/pypi/simple.py", line 320, in _process_url
    for link, is_download in link_matcher(f.read().decode(), base_url):
  File "/nix/var/nix/profiles/plone/lib/python2.7/site-packages/Distutils2-1.0a4-py2.7.egg/distutils2/pypi/simple.py", line 362, in _simple_link_matcher
    url = self._get_full_url(match.group(1), base_url)
  File "/nix/var/nix/profiles/plone/lib/python2.7/site-packages/Distutils2-1.0a4-py2.7.egg/distutils2/pypi/simple.py", line 349, in _get_full_url
    return urlparse.urljoin(base_url, self._htmldecode(url))
  File "/nix/var/nix/profiles/plone/lib/python2.7/site-packages/Distutils2-1.0a4-py2.7.egg/distutils2/pypi/simple.py", line 469, in _htmldecode
    return ENTITY_SUB(self._decode_entity, text)
  File "/nix/var/nix/profiles/plone/lib/python2.7/site-packages/Distutils2-1.0a4-py2.7.egg/distutils2/pypi/simple.py", line 463, in _decode_entity
    from html.entities import name2codepoint
ImportError: No module named html.entities