- Add trailing newline to tmpfiles.d/tmux.conf. On newer systems (such as Leap
15.1), the lack of a trailing newline appears to cause the directory to not
be created.

This is only evident on setups where /run is an actual tmpfs (on btrfs-root
installs, /run is a btrfs subvolume and thus /run/tmux is persistent across
reboots).