With 1.2-rolling-201910021249 the DHCP client doesn't automatically start on some interfaces, but it can still be started using the renew command.
I tracked this down to commit 35c7d6616 which now only start dhclient when the interface is really up. The problem seems to be that some interfaces (in my case a bond vif) take time to get to the 'up' state and the interface is still down when the addresses are added, so the DHCP client is not started.
For consistency set_state() should probably wait for the requested state to be effective before it return. Adding such a test to set_state() fix the problem on my system.