I checked that this did not happen on a system I just updated from 204 to 215; contents of /run/user/1000 remained unchanged after the upgrade.
Are you sure that the upgrade actually *removed* contents? A possibly relevant change is that logind started to mount a per-user tmpfs in /run/user/* (for per-user size limits). If something on your system triggered a mount of a new tmpfs over the existing directory, that could give similar symptoms. -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org