The bug is not present in 16.10 (yakkety, isc-dhcp-server=4.3.3-5ubuntu15.2). It is present in 17.10, 18.04 (isc-dhcp-server=4.3.5-3ubuntu7) and 18.10 (isc-dhcp-server=4.3.5-3ubuntu9). Not sure about 17.04.
The bug is not present in 16.10 (yakkety, isc-dhcp- server= 4.3.3-5ubuntu15 .2). It is present in 17.10, 18.04 (isc-dhcp- server= 4.3.5-3ubuntu7) and 18.10 (isc-dhcp- server= 4.3.5-3ubuntu9) . Not sure about 17.04.