--delete action prints "Bad file descriptor" due to insufficient privilege

[Maxim Cournoyer]

Hello,

I stumbled on the following output when attempting to delete a file from
a GNU tar produced archive, using GNU tar 1.34 on Guix:

--8<---------------cut here---------------start------------->8---
$ tar -f tar-pack.tar --delete './var/guix/db/db.sqlite'
tar: tar-pack.tar: Cannot read: Bad file descriptor
tar: At beginning of tape, quitting now
tar: Error is not recoverable: exiting now

$ echo $?
2

$ tar -tf tar-pack.tar.gz
./
./gnu/
./gnu/store/
./gnu/store/3yrfg1pzl4a0nl3qdgppb6dgmygw83f2-directory-with-utf8-file-names/
./gnu/store/3yrfg1pzl4a0nl3qdgppb6dgmygw83f2-directory-with-utf8-file-names/α
./gnu/store/3yrfg1pzl4a0nl3qdgppb6dgmygw83f2-directory-with-utf8-file-names/λ
./var/
./var/guix/
./var/guix/db/
./var/guix/db/db.sqlite
./var/guix/gcroots/
./var/guix/gcroots/profiles
./var/guix/profiles/
./var/guix/profiles/per-user/
./var/guix/profiles/per-user/root/
./var/guix/profiles/per-user/root/guix-profile
./var/guix/profiles/per-user/root/guix-profile-1-link
--8<---------------cut here---------------end--------------->8---

The problem seems to be with the files ownership; they are owned by
root.  Proceeding with 'sudo', it works normally:

--8<---------------cut here---------------start------------->8---
$ sudo tar -f tar-pack.tar --delete './var/guix/db/db.sqlite'
$ echo $?
0
--8<---------------cut here---------------end--------------->8---

So this bug report is about improving the error output so that it hints
at the insufficient privilege rather than the confusing "Bad file
descriptor" message.

I've attached the test tarball, in case it's useful (72 KiB).

tar-pack.tar
Description: archive/tar

-- 
Thanks,
Maxim