Comment 6 for bug 1399772

Directories in a pristine trusty VM after debootstrapping utopic and vivid:

$ ls -ld /{dev,run}/shm /tmp/{utopic,vivid}/{dev,run}/shm
ls: cannot access /tmp/vivid/run/shm: No such file or directory
lrwxrwxrwx 1 root root 8 Dec 18 18:37 /dev/shm -> /run/shm
drwxrwxrwt 2 root root 40 Dec 18 18:37 /run/shm
lrwxrwxrwx 1 root root 8 Dec 18 18:49 /tmp/utopic/dev/shm -> /run/shm
drwxr-xr-x 2 root root 4096 Dec 18 18:49 /tmp/utopic/run/shm
drwxr-xr-x 2 root root 4096 Dec 18 18:50 /tmp/vivid/dev/shm

So I suppose pbuilder takes care of /run/shm by mounting a tmpfs on it or bind-mounting it from the host. As wrong as https://wiki.debian.org/ReleaseGoals/RunDirectory is (and it seems the Debian sysvinit maintainers even have moved away from it, cf. the removed postinst code), it seems we need to go back there at least half way, until pbuilder etc. treat /dev/shm/ as the primary thing, and stop using /run/shm.

So either in vivid we need to create /run/shm/ again and the /dev/shm symlink to it, or at least make /dev/shm/ 1777.