Unable to set mac address to tap interface using systemd-networkd

I'm trying to migrate some tap interfaces setup from tunctl to systemd-networkd. I'm using systemd version 215-8. So I have this test.netdev file:

[Match]

[NetDev]
Name=tap_test
Kind=tap
MACAddress=1:2:3:4:5:6

and a test.network file:

[Match]
Name=tap_test

[Network]
Description=tap interface
Address=1.2.3.4/24

This suppose to replace the command

ifconfig tap_test \
1.2.3.4 \
netmask  255.255.255.0 \
hw ether 1:2:3:4:5:6 up

which used to be run after the tunctl command.

The result is fine except for the fact that the MAC address was not configured correctly. In the documentation of systemd (for 215 version) it says that the MAC address should be configured in the .netdev file in the [NETDEV] section. (I know, in later versions of systemd the MAC adress is configured in matching .network files, but this isn't the case)