the following patch broke NSH client

https://git.opendaylight.org/gerrit/#/c/23415/1

root@SFF-1-p:/vagrant/sfc-py/sfc# python3.4 sff_client.py --remote-sff-ip 192.168.33.31
--remote-sff-port 6633 --sfp-id 1 --sfp-index 255
ERROR:asyncio:Exception in callback <bound method MyVxlanGpeNshIpClient.connection_made
of <_main.MyVxlanGpeNshIpClient object at 0x7f52828a6f28>>(<asyncio.selector_events.
SelectorDatagramTransport object at 0x7f528296f748>,)
handle: Handle(<bound method MyVxlanGpeNshIpClient.connection_made of <_main_.MyVxlanG
peNshIpClient object at 0x7f52828a6f28>>, (<asyncio.selector_events._SelectorDatagramTra
nsport object at 0x7f528296f748>,))
Traceback (most recent call last):
File "/usr/lib/python3.4/asyncio/events.py", line 39, in _run
self._callback(*self._args)
File "sff_client.py", line 90, in connection_made
udp_packet = build_udp_packet(self.dest_addr, "10.0.1.1", 10000, self.dest_port, "te
st".encode('utf-8'))
File "/vagrant/sfc-py/sfc/nsh/encode.py", line 282, in build_udp_packet
ip_header, ip_header_pack = build_ipv4_header(total_len, socket.IPPROTO_UDP, src_ip,
dest_ip)
File "/vagrant/sfc-py/sfc/nsh/encode.py", line 237, in build_ipv4_header
ip_header = IPHEADER(IP_HEADER_LEN, IPV4_VERSION, IPV4_TOS, ip_tot_len, IPV4_PACKET_
ID, 0, IPV4_TTL, proto, 0,
NameError: name 'IPHEADER' is not defined