Thank you for letting me know I didn't do anything since yesterday that would have affected the system. ;)
Luckily, and that is why, I have double installations with one held back at least a day on updates (both testing), so now I am on number 2 looking at what is to be upgraded that was upgraded yesterday on the other. I also keep a common cache of pkgs so I can revert to the previous version from what was updated.
Actually it is not that bad, I only lost networking. ifconfig only shows lo, when I enable eth0 it does come up but fails to make a connection. Also connman-gtk gives errors. Other than that the desktop started and tty6 was fully functional.
Finally in the true spirit of testing!
[2018-02-28 00:09] [ALPM] upgraded kickshaw (0.5.22-1 -> 0.5.23-1)
[2018-02-28 00:09] [ALPM] upgraded libwacom (0.27-2 -> 0.28-3)
[2018-02-28 00:09] [ALPM] upgraded libinput (1.10.0-2 -> 1.10.0+25+g3e77f2e9-2)
[2018-02-28 00:09] [ALPM] upgraded obarun-build (0.1.4+2+gc7167b5-3 -> 0.1.5-1)
[2018-02-28 00:09] [ALPM] upgraded qt5-base (5.10.1-2 -> 5.10.1-3)
[2018-02-28 00:09] [ALPM] upgraded skalibs (2.6.2.0-1 -> 2.6.3.1-1)
[2018-02-28 00:09] [ALPM] upgraded s6 (2.6.2.0-1 -> 2.7.0.0-1)
[2018-02-28 00:09] [ALPM] upgraded s6-rc (0.3.0.1-1 -> 0.4.0.0-1)
[2018-02-28 00:09] [ALPM-SCRIPTLET] -> WARNING
[2018-02-28 00:09] [ALPM-SCRIPTLET] -> You need to compile again your root/user database with s6opts, for example:
[2018-02-28 00:09] [ALPM-SCRIPTLET] -> s6opts compile Live live
[2018-02-28 00:09] [ALPM] warning: /etc/s6/compiled/previous installed as /etc/s6/compiled/previous.pacnew
[2018-02-28 00:09] [ALPM] warning: /etc/s6/compiled/current installed as /etc/s6/compiled/current.pacnew
[2018-02-28 00:09] [ALPM] upgraded s6-boot (0.2.1-2 -> 0.2.1-3)
[2018-02-28 00:09] [ALPM] upgraded s6-dns (2.2.0.1-1 -> 2.3.0.0-1)
[2018-02-28 00:09] [ALPM] upgraded udisks2 (2.7.5-2 -> 2.7.6-2)
[2018-02-28 00:09] [ALPM] transaction completed