Description of problem:
# cat /etc/xinetd.d/tftp 
service tftp
{
	socket_type		= dgram
	protocol		= udp
	wait			= yes
	user			= root
	server			= /usr/sbin/in.tftpd
	server_args		= -s /var/lib/tftpboot
	disable			= no
	per_source		= 11
	cps			= 100 2
	flags			= IPv6
}

# service xinetd restart

# ls /var/lib/tftpboot
tst

# tftp -6 ::1
tftp> trace on
Packet tracing on.
tftp> verbose on
Verbose mode on.
tftp> get tst
getting from ::1:tst to tst [netascii]
sent RRQ <file=tst, mode=netascii>
sent RRQ <file=tst, mode=netascii>
sent RRQ <file=tst, mode=netascii>
sent RRQ <file=tst, mode=netascii>
sent RRQ <file=tst, mode=netascii>
Transfer timed out.
[transfer will never finish]

Version-Release number of selected component (if applicable):
tftp-server-5.1-1.el7.x86_64
tftp-5.1-1.el7.x86_64

How reproducible:
100%

Steps to Reproduce:
see description
  
Actual results:
Cannot download file with tftp client

Expected results:
No issues downloading file

Additional info:
This worked in RHEL6. The testcase works for both IPv4 and IPv6 if I use flags=IPv4