Gets killed trying to diff very large (~5GB) images

This bug was originally reported by Evangelos Ribeiro Tzaras (devrtz-debian@fortysixandtwo.eu) in Debian bug #1037075:

I was trying to see if Mobian images build for the Librem5 would be reproducible.
They were not.reproducible, so I wanted to run diffoscope on it, but sadly it get's killed:

> $ ls -l l5-phosh-{1,2}/mobian-librem5-phosh-20230603.img
- -rw-r--r-- 1 fortysixandtwo fortysixandtwo 6000000000 Jun  3 06:22 l5-phosh-1/mobian-librem5-phosh-20230603.img
- -rw-r--r-- 1 fortysixandtwo fortysixandtwo 6000000000 Jun  3 06:45 l5-phosh-2/mobian-librem5-phosh-20230603.img
> $ diffoscope --debug l5-phosh-{1,2}/mobian-librem5-phosh-20230603.img
2023-06-03 13:58:43 D: diffoscope.main: Starting diffoscope 242
2023-06-03 13:58:43 D: diffoscope.presenters.formats: Will generate the following presenter formats: text
2023-06-03 13:58:43 D: diffoscope.environ: Normalising locale, timezone, etc. PATH is /usr/lib/ccache:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/lib/x86_64-linux-gnu
2023-06-03 11:58:43 D: diffoscope.main: Starting comparison
2023-06-03 11:58:43 D: diffoscope.comparators: Loaded 90 comparator classes
2023-06-03 11:58:43 D: diffoscope.comparators.utils.specialize: l5-phosh-1/mobian-librem5-phosh-20230603.img not identified by any comparator. Magic says: DOS/MBR boot sector; partition 1 : ID=0xee, start-CHS (0x0,0,2), end-CHS (0x3ff,255,63), startsector 1, 11718749 sectors, extended partition table (last)
2023-06-03 11:58:43 D: diffoscope.comparators.utils.specialize: l5-phosh-2/mobian-librem5-phosh-20230603.img not identified by any comparator. Magic says: DOS/MBR boot sector; partition 1 : ID=0xee, start-CHS (0x0,0,2), end-CHS (0x3ff,255,63), startsector 1, 11718749 sectors, extended partition table (last)
2023-06-03 11:58:43 D: diffoscope.comparators.utils.compare: Comparing l5-phosh-1/mobian-librem5-phosh-20230603.img (FilesystemFile) and l5-phosh-2/mobian-librem5-phosh-20230603.img (FilesystemFile)
2023-06-03 11:58:43 D: diffoscope.comparators.utils.specialize: l5-phosh-1/mobian-librem5-phosh-20230603.img not identified by any comparator. Magic says: DOS/MBR boot sector; partition 1 : ID=0xee, start-CHS (0x0,0,2), end-CHS (0x3ff,255,63), startsector 1, 11718749 sectors, extended partition table (last)
2023-06-03 11:58:43 D: diffoscope.comparators.utils.specialize: l5-phosh-2/mobian-librem5-phosh-20230603.img not identified by any comparator. Magic says: DOS/MBR boot sector; partition 1 : ID=0xee, start-CHS (0x0,0,2), end-CHS (0x3ff,255,63), startsector 1, 11718749 sectors, extended partition table (last)
2023-06-03 11:58:43 D: diffoscope.comparators.utils.file: has_same_content(l5-phosh-1/mobian-librem5-phosh-20230603.img, l5-phosh-2/mobian-librem5-phosh-20230603.img)
2023-06-03 11:58:43 D: diffoscope.comparators.utils.command: Executing xxd {}
[1]    21386 killed     diffoscope --debug l5-phosh-{1,2}/mobian-librem5-phosh-20230603.img

Holger added:

> thanks Evangelos, for filing this bug and providing the images exposing it to
> https://fortysixandtwo.eu/upload/mobian-librem5-phosh-20230603-{1,2}.img now.