Verification for Xenial:

ubuntu@dixie:~$ uname -a
Linux dixie 4.4.0-31-generic #50-Ubuntu SMP Wed Jul 13 00:07:12 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

ubuntu@dixie:~$ lsb_release -a
No LSB modules are available.
Distributor ID:	Ubuntu
Description:	Ubuntu 16.04.1 LTS
Release:	16.04
Codename:	xenial

ubuntu@dixie:~$ dpkg -l | grep isc-dhcp
ii  isc-dhcp-client                    4.3.3-5ubuntu12.1               amd64        DHCP client for automatically obtaining an IP address
ii  isc-dhcp-common                    4.3.3-5ubuntu12.1               amd64        common files used by all of the isc-dhcp packages
ii  isc-dhcp-server                    4.3.3-5ubuntu12.1               amd64        ISC DHCP server for automatic IP address assignment

You can observe that DHCP works AND broadcast flag is set (by sniffing dhcp server ib0 interface):

ubuntu@dixie:~$ sudo tcpdump -i ib0 -nn -vvv -S
tcpdump: listening on ib0, link-type LINUX_SLL (Linux cooked), capture size 262144 bytes
16:21:22.603191 IP (tos 0x10, ttl 128, id 0, offset 0, flags [none], proto UDP (17), length 328)
    0.0.0.0.68 > 255.255.255.255.67: [udp sum ok] BOOTP/DHCP, Request, length 300, htype 32, hlen 0, xid 0x6775c96f, Flags [Broadcast] (0x8000)
	  Vendor-rfc1048 Extensions
	    Magic Cookie 0x63825363
	    DHCP-Message Option 53, length 1: Discover
	    Hostname Option 12, length 5: "hertz"
	    Parameter-Request Option 55, length 13: 
	      Subnet-Mask, BR, Time-Zone, Default-Gateway
	      Domain-Name, Domain-Name-Server, Option 119, Hostname
	      Netbios-Name-Server, Netbios-Scope, MTU, Classless-Static-Route
	      NTP
	    Client-ID Option 61, length 17: hardware-type 56, 30:3a:30:30:3a:30:30:3a:34:38:3a:46:45:3a:38:30
	    END Option 255, length 0
	    PAD Option 0, length 0, occurs 15
16:21:22.603401 IP (tos 0x10, ttl 128, id 0, offset 0, flags [none], proto UDP (17), length 328)
    172.16.0.1.67 > 255.255.255.255.68: [udp sum ok] BOOTP/DHCP, Reply, length 300, htype 32, hlen 0, xid 0x6775c96f, Flags [Broadcast] (0x8000)
	  Your-IP 172.16.0.19
	  Server-IP 172.16.0.1
	  Vendor-rfc1048 Extensions
	    Magic Cookie 0x63825363
	    DHCP-Message Option 53, length 1: Offer
	    Server-ID Option 54, length 4: 172.16.0.1
	    Lease-Time Option 51, length 4: 600
	    Subnet-Mask Option 1, length 4: 255.255.255.0
	    BR Option 28, length 4: 172.16.0.255
	    Domain-Name Option 15, length 7: "myib.cu"
	    END Option 255, length 0
	    PAD Option 0, length 0, occurs 23
16:21:22.603586 IP (tos 0x10, ttl 128, id 0, offset 0, flags [none], proto UDP (17), length 328)
    0.0.0.0.68 > 255.255.255.255.67: [udp sum ok] BOOTP/DHCP, Request, length 300, htype 32, hlen 0, xid 0x6775c96f, Flags [Broadcast] (0x8000)
	  Vendor-rfc1048 Extensions
	    Magic Cookie 0x63825363
	    DHCP-Message Option 53, length 1: Request
	    Server-ID Option 54, length 4: 172.16.0.1
	    Requested-IP Option 50, length 4: 172.16.0.19
	    Hostname Option 12, length 5: "hertz"
	    Parameter-Request Option 55, length 13: 
	      Subnet-Mask, BR, Time-Zone, Default-Gateway
	      Domain-Name, Domain-Name-Server, Option 119, Hostname
	      Netbios-Name-Server, Netbios-Scope, MTU, Classless-Static-Route
	      NTP
	    Client-ID Option 61, length 17: hardware-type 56, 30:3a:30:30:3a:30:30:3a:34:38:3a:46:45:3a:38:30
	    END Option 255, length 0
	    PAD Option 0, length 0, occurs 3
16:21:22.603758 IP (tos 0x10, ttl 128, id 0, offset 0, flags [none], proto UDP (17), length 328)
    172.16.0.1.67 > 255.255.255.255.68: [udp sum ok] BOOTP/DHCP, Reply, length 300, htype 32, hlen 0, xid 0x6775c96f, Flags [Broadcast] (0x8000)
	  Your-IP 172.16.0.19
	  Server-IP 172.16.0.1
	  Vendor-rfc1048 Extensions
	    Magic Cookie 0x63825363
	    DHCP-Message Option 53, length 1: ACK
	    Server-ID Option 54, length 4: 172.16.0.1
	    Lease-Time Option 51, length 4: 600
	    Subnet-Mask Option 1, length 4: 255.255.255.0
	    BR Option 28, length 4: 172.16.0.255
	    Domain-Name Option 15, length 7: "myib.cu"
	    END Option 255, length 0
	    PAD Option 0, length 0, occurs 23

Everything looks good!!