When the page length is less than 10, pr does not output a header, even
one that is explicitly supplied.
Stated another way, when page length is <= 10, there is no way to
counter implicit -t/-T.
Stated another way, -t/-T always (silently) overrides -h, and there is
no option to force a header.
This is in $ pr --version
pr (GNU coreutils) 8.32
Copyright (C) 2020 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later
<https://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Written by Pete TerMaat and Roland Huebner.
Example to reproduce:
$ printf "a\nb\nc\nd\\ne\n" | pr -l 3 -h "---"
a
b
c
d
e
luke
