PriorityInheritance doesn't work (tinc 1.0.19)

[SVM]

Hello!

I'd like to use PriorityInheritance option, despite it is still 
experimental. (Why it could be experimental, when it looks quite simple 
feature, no?)
But this option doesn't change the TOS field of outgoing UDP packet.

I just do tcpdump on outgoing interface from vty1:
$ sudo tcpdump -vni eth0 udp dst port 655

And from vty2 I do ping with setting of tos field to EF(0xb8).
$ ping -c1 <remote-ip-addr-on-tap-device> -Q 0xb8

And on outgoing interface I can only see the folowing from tcpdump:
IP(tos 0x0, ttl 64, id 0, offset 0, flags[DF], proto UDP(17), length 136

So the TOS field doesn't take the value from TOS of encapsulated packet.

Is this a bug or I do something wrong?

Thank you in advance.

===
$ tinc.conf $
Name = eiger
Interface = tap1
Mode = switch

MaxTimeout = 120
PriorityInheritance = yes

ConnectTo = pika
===