ifup@.service doesn't work with interface names containing a dash

It seems dashes get replaced by forward slash in the unit file and hence the interface is not found.
Endresult is that the interface does not come up.

$ sudo systemctl start ifup@br-vxlan
$ # I'm expecting this brings up the br-vxlan, but nothing happens, this command doesn't return an error message

Further info:

$ sudo systemctl status ifup@br-vxlan
* <email address hidden> - ifup for br/vxlan
   Loaded: loaded (/lib/systemd/system/ifup@.service; static; vendor preset: enabled)
   Active: active (exited) since Mon 2017-01-09 15:55:15 CET; 10min ago
  Process: 4705 ExecStop=/sbin/ifdown %I (code=exited, status=1/FAILURE)
  Process: 4713 ExecStart=/bin/sh -ec ifup --allow=hotplug %I; ifup --allow=auto %I; if ifquery %I >/dev/
 Main PID: 4713 (code=exited, status=0/SUCCESS)
   CGroup: /<email address hidden>

Jan 09 15:55:15 xxxxxxxxxxx systemd[1]: Started ifup for br/vxlan.
Jan 09 15:55:15 xxxxxxxxxxx sh[4713]: Unknown interface br/vxlan

$ cat /etc/network/interfaces.d/60_iface_br-vxlan

allow-auto br-vxlan
allow-boot br-vxlan
allow-hotplug br-vxlan
iface br-vxlan inet manual
    bridge_fd 0
    bridge_maxwait 0
    bridge_ports enp1s0f1
    bridge_stp off
    bridge_waitport 0

$ lsb_release -rd
Description: Ubuntu 16.04.1 LTS
Release: 16.04

$ apt-cache policy ifupdown
ifupdown:
  Installed: 0.8.10ubuntu1.2
  Candidate: 0.8.10ubuntu1.2
  Version table:
 *** 0.8.10ubuntu1.2 500
        500 http://xxxxxxx.cisco.com/ubuntu xenial-updates/main amd64 Packages
        100 /var/lib/dpkg/status
     0.8.10ubuntu1 500
        500 http://xxxxxxx.cisco.com/ubuntu xenial/main amd64 Packages