when running test-debug, following assert is seen

(gdb) bt
#0 __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:51
#1 0x00007f7626ceb801 in __GI_abort () at abort.c:79
#2 0x0000559b9cb647f9 in os_panic () at /home/ksekera/vpp/build-data/../src/vpp/vnet/main.c:310
#3 0x00007f76274f0738 in debugger () at /home/ksekera/vpp/build-data/../src/vppinfra/error.c:84
#4 0x00007f76274f0b73 in _clib_error (how_to_die=2, function_name=0x0, line_number=0, fmt=0x7f76285b7dc0 "%s:%d (%s) assertion `%s' fails")
at /home/ksekera/vpp/build-data/../src/vppinfra/error.c:143
#5 0x00007f7627d0b9e1 in ip4_rewrite_inline (vm=0x7f7628ceba00 <vlib_global_main>, node=0x7f75e6349e80, frame=0x7f75e6402b80, do_counters=0,
is_midchain=0, is_mcast=0) at /home/ksekera/vpp/build-data/../src/vnet/ip/ip4_forward.c:2176
#6 0x00007f7627d0c906 in ip4_rewrite (vm=0x7f7628ceba00 <vlib_global_main>, node=0x7f75e6349e80, frame=0x7f75e6402b80)
at /home/ksekera/vpp/build-data/../src/vnet/ip/ip4_forward.c:2521
#7 0x00007f7628a3dab4 in dispatch_node (vm=0x7f7628ceba00 <vlib_global_main>, node=0x7f75e6349e80, type=VLIB_NODE_TYPE_INTERNAL,
dispatch_state=VLIB_NODE_STATE_POLLING, frame=0x7f75e6402b80, last_time_stamp=2878367439307058)
at /home/ksekera/vpp/build-data/../src/vlib/main.c:988
#8 0x00007f7628a3e06d in dispatch_pending_node (vm=0x7f7628ceba00 <vlib_global_main>, pending_frame_index=6, last_time_stamp=2878367439307058)
at /home/ksekera/vpp/build-data/../src/vlib/main.c:1138
#9 0x00007f7628a403af in vlib_main_or_worker_loop (vm=0x7f7628ceba00 <vlib_global_main>, is_main=1)
at /home/ksekera/vpp/build-data/../src/vlib/main.c:1616
#10 0x00007f7628a4045d in vlib_main_loop (vm=0x7f7628ceba00 <vlib_global_main>) at /home/ksekera/vpp/build-data/../src/vlib/main.c:1635
#11 0x00007f7628a41030 in vlib_main (vm=0x7f7628ceba00 <vlib_global_main>, input=0x7f75e6c8dfb0)
at /home/ksekera/vpp/build-data/../src/vlib/main.c:1826
#12 0x00007f7628aae127 in thread0 (arg=140145467505152) at /home/ksekera/vpp/build-data/../src/vlib/unix/main.c:570
#13 0x00007f7627515474 in clib_calljmp () at /home/ksekera/vpp/build-data/../src/vppinfra/longjmp.S:110
#14 0x00007fff4c9afd20 in ?? ()
#15 0x00007f7628aae5a5 in vlib_unix_main (argc=27, argv=0x7fff4c9b0f78) at /home/ksekera/vpp/build-data/../src/vlib/unix/main.c:634
#16 0x0000559b9cb6423d in main (argc=27, argv=0x7fff4c9b0f78) at /home/ksekera/vpp/build-data/../src/vpp/vnet/main.c:249