"TypeError: unhashable type: 'InterfaceClass'" in Python 3

I don't think 'id(self)' is the right hash value: items which compare equal are also supposed to have the same hash value. Likely we should be using the hash of the fully-qualified name.

To get the buildout bootstrapped under Python3, I did::

 $ svn cat svn://svn.zope.org/repos/main/zc.buildout/branches/2/bootstrap/bootstrap.py > boostrap3.py
 $ /opt/Python-3.2.0/bin/python3 boostrap.py
 ...

Note that the Sphinx dependencies for the 'docs' part won't build, so skip that part::

 $ bin/buildout install test python

but I can't run the tests::

 $ bin/test --all
 Traceback (most recent call last):
   File "bin/test", line 20, in <module>
     import zope.testrunner
   File "/tmp/zi/src/zope.interface/eggs/zope.testrunner-4.0.3-py3.2.egg/zope/testrunner/__init__.py", line 21, in <module>
     import zope.testrunner.interfaces
   File "/tmp/zi/src/zope.interface/eggs/zope.testrunner-4.0.3-py3.2.egg/zope/testrunner/interfaces.py", line 21, in <module>
     import zope.interface
   File "/tmp/zi/src/zope.interface/src/zope/interface/__init__.py", line 53, in <module>
     from zope.interface.interface import Interface, _wire
   File "/tmp/zi/src/zope.interface/src/zope/interface/interface.py", line 577
     exec "class %s: pass" % self.__name__ in klass
                         ^
 SyntaxError: invalid syntax

Turns out the only sane way to test zope.interface under Python3 is:

  $ /path/to/nonvirtual/Python-3.x/bin/python3 setup.py test

Released a fix with zope.interface 3.6.4:
  http://pypi.python.org/pypi/zope.interface/3.6.4