Crash when splitting chunk

[wezm]

With tig in the following state, pressing \ to call stage-split-chunk causes a crash for me every time.

The error/backtrace reported is:

** Error in `tig': realloc(): invalid next size: 0x000000000216af60 ***
======= Backtrace: =========
/usr/lib/libc.so.6(+0x70c4b)[0x7f4c8809ac4b]
/usr/lib/libc.so.6(+0x76fe6)[0x7f4c880a0fe6]
/usr/lib/libc.so.6(+0x79fcc)[0x7f4c880a3fcc]
/usr/lib/libc.so.6(realloc+0x159)[0x7f4c880a54f9]
tig[0x40602e]
tig[0x418db3]
tig[0x419018]
tig[0x4190cc]
tig[0x421908]
tig[0x4223dd]
tig[0x40371a]
/usr/lib/libc.so.6(__libc_start_main+0xf1)[0x7f4c8804a291]
tig[0x40400a]
======= Memory map: ========
00400000-0043a000 r-xp 00000000 08:02 3823205                            /usr/bin/tig
00639000-0063a000 r--p 00039000 08:02 3823205                            /usr/bin/tig
0063a000-00647000 rw-p 0003a000 08:02 3823205                            /usr/bin/tig
00647000-00650000 rw-p 00000000 00:00 0
01ec7000-021e9000 rw-p 00000000 00:00 0                                  [heap]
7f4c83de9000-7f4c83dff000 r-xp 00000000 08:02 3804638                    /usr/lib/libgcc_s.so.1
7f4c83dff000-7f4c83ffe000 ---p 00016000 08:02 3804638                    /usr/lib/libgcc_s.so.1
7f4c83ffe000-7f4c83fff000 r--p 00015000 08:02 3804638                    /usr/lib/libgcc_s.so.1
7f4c83fff000-7f4c84000000 rw-p 00016000 08:02 3804638                    /usr/lib/libgcc_s.so.1
7f4c84000000-7f4c84021000 rw-p 00000000 00:00 0
7f4c84021000-7f4c88000000 ---p 00000000 00:00 0
7f4c8802a000-7f4c881bf000 r-xp 00000000 08:02 3804325                    /usr/lib/libc-2.24.so
7f4c881bf000-7f4c883be000 ---p 00195000 08:02 3804325                    /usr/lib/libc-2.24.so
7f4c883be000-7f4c883c2000 r--p 00194000 08:02 3804325                    /usr/lib/libc-2.24.so
7f4c883c2000-7f4c883c4000 rw-p 00198000 08:02 3804325                    /usr/lib/libc-2.24.so
7f4c883c4000-7f4c883c8000 rw-p 00000000 00:00 0
7f4c883c8000-7f4c8842f000 r-xp 00000000 08:02 3804718                    /usr/lib/libncursesw.so.6.0
7f4c8842f000-7f4c8862f000 ---p 00067000 08:02 3804718                    /usr/lib/libncursesw.so.6.0
7f4c8862f000-7f4c88633000 r--p 00067000 08:02 3804718                    /usr/lib/libncursesw.so.6.0
7f4c88633000-7f4c88635000 rw-p 0006b000 08:02 3804718                    /usr/lib/libncursesw.so.6.0
7f4c88635000-7f4c88675000 r-xp 00000000 08:02 3807362                    /usr/lib/libreadline.so.6.3
7f4c88675000-7f4c88875000 ---p 00040000 08:02 3807362                    /usr/lib/libreadline.so.6.3
7f4c88875000-7f4c88877000 r--p 00040000 08:02 3807362                    /usr/lib/libreadline.so.6.3
7f4c88877000-7f4c8887d000 rw-p 00042000 08:02 3807362                    /usr/lib/libreadline.so.6.3
7f4c8887d000-7f4c8887f000 rw-p 00000000 00:00 0
7f4c8887f000-7f4c888a2000 r-xp 00000000 08:02 3804324                    /usr/lib/ld-2.24.so
7f4c888ec000-7f4c88a85000 r--p 00000000 08:02 3836163                    /usr/lib/locale/locale-archive
7f4c88a85000-7f4c88a89000 rw-p 00000000 00:00 0
7f4c88aa0000-7f4c88aa1000 rw-p 00000000 00:00 0
7f4c88aa1000-7f4c88aa2000 r--p 00022000 08:02 3804324                    /usr/lib/ld-2.24.so
7f4c88aa2000-7f4c88aa3000 rw-p 00023000 08:02 3804324                    /usr/lib/ld-2.24.so
7f4c88aa3000-7f4c88aa4000 rw-p 00000000 00:00 0
7ffd851ea000-7ffd8520b000 rw-p 00000000 00:00 0                          [stack]
7ffd85332000-7ffd85334000 r--p 00000000 00:00 0                          [vvar]
7ffd85334000-7ffd85336000 r-xp 00000000 00:00 0                          [vdso]
ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0                  [vsyscall]
[1]    14994 abort (core dumped)  tig status

OS: Arch Linux
uname: Linux wes-linux-box 4.7.1-1-ARCH #1 SMP PREEMPT Wed Aug 17 08:13:35 CEST 2016 x86_64 GNU/Linux
tig version: 2.2

The problematic diff is attached in case it is useful:

crashing-diff.txt

[wezm]

Thank you @xaizek!