https://bugzilla.wikimedia.org/show_bug.cgi?id=70760
--- Comment #4 from Fabian CommodoreFabianus@gmx.de --- I'm currently working on a fix, or to be more specific I 'have' one but I don't get what I expect.
Depending on how git savy you are: https://github.com/xZise/pywikibot-core/commit/a44818b139c0e4168ff8a6b92546e... should fix it, but this is what I get: http://paste.ubuntu.com/8325881/
(It looks like the same error, but it doesn't find a 'csrf' token and not an 'edit' token like in your case and that's because when something is requesting an edit token it actually requests a csrf token.)