I've upgraded to 2.3.1/2 and I can confirm that this behavior has regressed:
option domain-name-servers 10.90.90.1, 10.90.90.1;
I've upgraded to 2.3.1/2 and I can confirm that this behavior has regressed:
option domain-name-servers 10.90.90.1, 10.90.90.1;