I noticed that there's a bug in the getOldVersion() method in page.py.
The error is in line 309, when it calls site.loadrevisions() the
third parameter is 'revids=oldid'. loadrevisions() attempts to
iterate over that, and fails. The doc for getOldVersion() says
'oldid' should be "the revid of the revision desired", so I patched
line 309 to use 'revids=[oldid]', and that seems to work just fine.