bug#50096: args-out-of-range in redisplay_internal

[Juri Linkov]

> So we are in the wrong (empty) buffer?  Or did someone delete the
> buffer's text under our feet?  What does this show:
>
>   (gdb) p object->name_
>   (gdb) xstring
>   (gdb) p current_buffer->name_
>   (gdb) xstring

(gdb) p XBUFFER (object)->name_
$7 = XIL(0x7f015341fb84)
(gdb) xstring
$8 = (struct Lisp_String *) 0x7f015341fb80
" *Minibuf-0*"
(gdb) p current_buffer->name_
$9 = XIL(0x7f015341fb84)
(gdb) xstring
$10 = (struct Lisp_String *) 0x7f015341fb80
" *Minibuf-0*"

PS: Some commit between e2eb58c487 and 31ab12e261 broke that,
but maybe this is not important because these commits
just changed the length of the git command by adding ":(literal)",
and length change maybe exposed some other problem.