Comment 7 for bug 1389891

> which ones of /run/shm or /dev/shm is the current default standard?

That's a bit undefined. The upstream glibc standard is /dev/shm/; Debian introduced /run/shm/ a while ago essentially because "it looks nicer" (https://wiki.debian.org/ReleaseGoals/RunDirectory), which led to all this confusion and complicated postinst code to move directories and symlinks back and forth :-(

So in essence, we either need /dev/shm -> /run/shm/, or /run/shm -> /dev/shm/.