bug#54770: Non-root LUKS devices unusable after Shepherd upgrade

["Ludovic Courtès" <ludo@gnu.org>]

Hi!

Following the Shepherd upgrade in commit
400c9ed3d779308e56038305d40cd93acb496180, attempts to open non-root LUKS
devices from a Shepherd service fail with this cryptsetup message:

  Nothing to read on input.

This is because standard input is now /dev/null so it cannot read the
passphrase.

This is because “shepherd.conf” now does:

    (start-in-the-background …)

    (redirect-port (open-input-file "/dev/null")
                   (current-input-port))

… meaning that ‘redirect-port’ is now called before services are
started.

‘fsck’ invocations for non-root file systems (started from Shepherd
services) would have the same problem.

I’ll try and come up with a solution…

Ludo’.