I think that wikipedia.Page.getVersionHistory has a bug. The function getVersionHistory return without edit summary at least in Japanese Wikipedia.
The local variable editR is wrong. The following version may work:
editR = re.compile(r'<li>([^)]*) ([^)]*) <[^>]*><[^>]*> <a href="[^'"]*oldid=(\d*)"[^>]*>([^<]*)</a> <span class=['"]history-user['"]><a [^>]*>([^<]*)</a>(?:[^<]|<(?!span class="comment">)(?!/li>))*(?:<span class="comment">((.*))</span>)?.*</li>', re.UNICODE)
I've tested this code rough.
Sorry for my poor English. Thank you. ---- [[w:ja:user:mizusumashi]]