This test seems to fail, maybe because of high inode numbers, maybe
something to with btrfs.

I saw this with the failed builds here
https://data.guix.gnu.org/gnu/store/kg93i3bmvpdfkiqyx6g9r7ywh0xpvm8w-guix-1.4.0


cbaines@milano-guix-1 ~$ guix repl
GNU Guile 3.0.8
Copyright (C) 1995-2021 Free Software Foundation, Inc.

Guile comes with ABSOLUTELY NO WARRANTY; for details type `,show w'.
This program is free software, and you are welcome to redistribute it
under certain conditions; type `,show c' for details.

Enter `,help' for help.
scheme@(guix-user)> (use-modules (guix cpio))
scheme@(guix-user)> (file->cpio-header "guix/guix.scm")
$1 = #<<cpio-header> magic: 460545 ino: 5031515288 mode: 33188 uid: 1003 gid: 998 nlink: 1 mtime: 1671460627 file-size: 1452 dev-maj: 0 dev-min: 24 rdev-maj: 0 rdev-min: 0 name-size: 14 checksum: 0>
scheme@(guix-user)> (use-modules (rnrs io ports))
scheme@(guix-user)> (define header $1)
scheme@(guix-user)> (call-with-values
        (lambda ()
          (open-bytevector-output-port))
      (lambda (port get-bv)
        (write-cpio-header header port)
        (let ((port (open-bytevector-input-port (get-bv))))
          (equal? header (read-cpio-header port)))))
$2 = #f
scheme@(guix-user)>     (call-with-values
        (lambda ()
          (open-bytevector-output-port))
      (lambda (port get-bv)
        (write-cpio-header header port)
        (let ((port (open-bytevector-input-port (get-bv))))
          (equal? (peek "A" header)
                  (peek "B" (read-cpio-header port))))))

;;; ("A" #<<cpio-header> magic: 460545 ino: 5031515288 mode: 33188 uid: 1003 gid: 998 nlink: 1 mtime: 1671460627 file-size: 1452 dev-maj: 0 dev-min: 24 rdev-maj: 0 rdev-min: 0 name-size: 14 checksum: 0>)

;;; ("B" #<<cpio-header> magic: 460545 ino: 736547992 mode: 33188 uid: 1003 gid: 998 nlink: 1 mtime: 1671460627 file-size: 1452 dev-maj: 0 dev-min: 24 rdev-maj: 0 rdev-min: 0 name-size: 14 checksum: 0>)
$3 = #f