description line in route-maps leaks memory

[donaldsharp]

master version:

commit 87b42ba

Running this command w/ zebra running:
eva# conf
eva(config)# route-map FOO permit 10
eva(config-route-map)# description I am a cheeseburger
eva(config-route-map)# end

When zebra stops we receive:

^C2020/06/30 21:24:51 ZEBRA: Terminating on signal
2020/06/30 21:24:51 ZEBRA: Zebra final shutdown

=================================================================
==122726==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 20 byte(s) in 1 object(s) allocated from:
#0 0x7fd8e305e0b5 in strdup (/lib/x86_64-linux-gnu/libasan.so.5+0x920b5)
#1 0x7fd8e2d8cee0 in qstrdup lib/memory.c:122
#2 0x7fd8e2dfa65d in lib_route_map_entry_description_modify lib/routemap_northbound.c:205
#3 0x7fd8e2da46a8 in nb_callback_modify lib/northbound.c:901
#4 0x7fd8e2da668a in nb_callback_configuration lib/northbound.c:1167
#5 0x7fd8e2da6ce7 in nb_transaction_process lib/northbound.c:1288
#6 0x7fd8e2da3169 in nb_candidate_commit_prepare lib/northbound.c:706
#7 0x7fd8e2da378e in nb_candidate_commit lib/northbound.c:749
#8 0x7fd8e2db5145 in nb_cli_apply_changes lib/northbound_cli.c:168
#9 0x7fd8e2df9535 in rmap_description_magic lib/routemap_cli.c:1028
#10 0x7fd8e2df50e4 in rmap_description lib/routemap_cli_clippy.c:1968
#11 0x7fd8e2d04779 in cmd_execute_command_real lib/command.c:909
#12 0x7fd8e2d04aee in cmd_execute_command lib/command.c:969
#13 0x7fd8e2d05649 in cmd_execute lib/command.c:1122
#14 0x7fd8e2e4c9f5 in vty_command lib/vty.c:526
#15 0x7fd8e2e5150f in vty_execute lib/vty.c:1293
#16 0x7fd8e2e5635b in vtysh_read lib/vty.c:2126
#17 0x7fd8e2e3e4a1 in thread_call lib/thread.c:1550
#18 0x7fd8e2d7f0a8 in frr_run lib/libfrr.c:1098
#19 0x55e1a3d48685 in main zebra/main.c:503
#20 0x7fd8e2a70e0a in __libc_start_main ../csu/libc-start.c:308