Comment # 2 on bug 940522 from Marius Tomaschewski

(In reply to Jiri Slaby from comment #1)
> vpn start is the trigger.

VPN does not tweak any mounts. It is using systemd-ask-password to
ask for a password and this triggers the mount as the log indicate.

IMO as defined in /usr/lib/systemd/system/tmp.mount:

[Unit]
ConditionPathIsSymbolicLink=!/tmp

[Mount]
What=tmpfs
Where=/tmp
Type=tmpfs
Options=mode=1777,strictatime

On my leap system (no /tmp in fstab), /tmp is a dir on /-fs ...:

# df -h /tmp
Filesystem      Size  Used Avail Use% Mounted on
/dev/sda2        15G  6.3G  7.7G  46% /

not a link. So something seems fishy / inconsistent here.