I ran git bisect on keystone and turns out the culprit is the commit ed13c0e5d4ceb55a1180e2818a425dc6c60420a9 (before that one logging into Horizon works fine).
I ran git bisect on keystone and turns out the culprit is the commit ed13c0e5d4ceb55 a1180e2818a425d c6c60420a9 (before that one logging into Horizon works fine).