thunar can't mount USB drive: not authorized

[Ernest Adrogué]

Hi,

I have some kind of permissions problem, probably related to systemd.  When
I plug a USB drive and try to mount it with thunar, it says "not authorized
to perform operation".  The drive can be mounted with udisks from the
command line

1|ernest at doriath:~$ udisksctl mount -b /dev/sdg1
==== AUTHENTICATING FOR org.freedesktop.udisks2.filesystem-mount-other-seat
===
Authentication is required to mount SMI USB DISK (/dev/sdg1)
Authenticating as: Ernest A C,,, (ernest)
Password:
==== AUTHENTICATION COMPLETE ===
Mounted /dev/sdg1 at /media/ernest/37FA-40B4.

I noticed that now I can't suspend, shutdown or reboot as normal user
either.  I'm using Debian testing, XFCE 4.12, systemd-shim and sys V init.

Any hint appreciated.