Comment 22 for bug 1545707

Tested on 2 xenial install: one fresh, and a wily to xenial dist-upgrade: get the same result

oem@u64:~$ sudo find /{etc,lib,run}/systemd -name tmp.mount | xargs ls -l
[sudo] password for oem:
total 261428
-rw------- 1 oem oem 267624448 Feb 12 07:42 core
drwxr-xr-x 2 oem oem 4096 Sep 1 2014 Desktop
drwxr-xr-x 2 oem oem 4096 Apr 16 08:39 Documents
drwxr-xr-x 2 oem oem 4096 Apr 4 13:06 Downloads
-rw-r--r-- 1 oem oem 8980 Aug 29 2014 examples.desktop
drwxrwxr-x 3 oem oem 4096 Nov 1 06:33 git
drwxrwxr-x 3 oem oem 4096 Aug 30 2014 git_projects
-rw-rw-r-- 1 oem oem 493 Apr 10 17:36 hdparm.txt
drwxr-xr-x 2 oem oem 4096 Mar 14 17:05 kern
drwxr-xr-x 2 oem oem 4096 Aug 29 2014 Music
-rw------- 1 oem oem 9924 Apr 3 13:58 nohup.out
drwxr-xr-x 2 oem oem 4096 Mar 24 2015 Pictures
drwxr-xr-x 2 oem oem 4096 Aug 29 2014 Public
drwxr-xr-x 2 oem oem 4096 Aug 29 2014 Templates
drwxr-xr-x 2 oem oem 4096 Aug 29 2014 Videos

On both install, tmp.mount is only found into /usr/share/systemd/, like #20 above let suppose too.