pywikibot compat is broken since mediawiki release 1.28 due to login error. [1]
Deprecation of compat was announced long time ago [2][3][4][5][and some others]. I guess it is time to close this branch now. Anyway if one wants to fix this breaker, do it. Personally I would not like to investigate deeper in this matter and keeping compat still alive.
Greetings
xqt
[1] https://phabricator.wikimedia.org/T150613 [2] https://www.mediawiki.org/w/index.php?title=Manual:Pywikibot/Version_table&a... [3] https://www.mediawiki.org/w/index.php?title=Manual:Pywikibot/Compat/deprecat... [4] https://phabricator.wikimedia.org/T99365 [5] https://phabricator.wikimedia.org/T101524