Iterating over site.allpages() (in my case with namespace=0 and filterredir=False) causes a call to page.editTime() to fail with a KeyError. Closer inspection shows that _revid is set for pages in the generator, but _revisions is an empty dictionary. So latestRevision() returns _revid with no corresponding revision in _revisions, and the KeyError is thrown.
I'm running the rewrite branch, revision 9274, on Python 2.7 on Linux.
Fixed in r9379