Yury Selivanov added the comment:
Attaching a new patch, with all previous issues resolved.
Version dropdown can be enabled by the new 'pydoc_versionswitcher' config property (False by default).
Please review and test (I've done lots of testing by injecting the JS on live python docs site, but maybe missed something.)
---------- Added file: http://bugs.python.org/file27737/py3_version_switch.2.patch