As mentioned in https://github.com/fish-shell/fish-shell/issues/12055#issuecomment-3554869126
> instances of `/bin/sh` as freestanding commands within `.fish`
> files are most likely not automatically handled by `termux-exec`
and
> This topic is complicated by the fact that some Android ROMs _do_
> contain real `/bin/sh` files
Core uses /system/bin/sh on Android. Let's do the same from script
(even if /bin/sh exists), for consistency.
