bug#64686: 30.0.50; Tar mode @PaxHeader bug

[Eli Zaretskii]

> Date: Mon, 17 Jul 2023 14:31:39 -0400
> From: Devon Sean McCullough <emacs-hacker2017@jovi.net>
> 
> $ wget 
> https://f-droid.org/repo/com.simplemobiletools.voicerecorder_36_src.tar.gz
> $ emacs --no-init-file --no-site-file 
> com.simplemobiletools.voicerecorder_36_src.tar.gz
> 
> should show something like the output of
> 
> $ tar -tvz < com.simplemobiletools.voicerecorder_36_src.tar.gz
> 
> instead of spurious ././@PaxHeader lines
> interleaved with truncated long file names.

Thanks.  In a nutshell, tar-mode didn't support Posix-standard pax
extended headers.  Should be fixed now on the master branch.

P.S. Thanks to Stefan who found a subtle bug in the prototype of this
fix.