https://bugs.freedesktop.org/show_bug.cgi?id=108992
--- Comment #9 from Brian Schott briancschott@gmail.com --- 020aa2ec15fc4a5ffdfcab7dc0db648a137abc41 lets me log in before the system freezes.
770af5859d6903049b7f39ed4f4e6612b63fd82d locks up before LightDM can start.
I'll do a bit more testing.