GPG: --default-key ignored

A script that updated and signs my Dreambox .deb package repository's Release file broke from one day to the next:

$ echo "password" | gpg --quiet --no-tty --batch --passphrase-fd=0 --default-key 15E60BE8 --detach-sign -o Release.gpg.tmp Release 
gpg: Alle für '--default-key' angegebenen Werte wurden ignoriert
gpg: no default secret key: Kein geheimer Schlüssel
gpg: signing failed: Kein geheimer Schlüssel

The reason for the failure was that the key was expired:

$ gpg --list-keys
gpg: "Trust-DB" wird überprüft
gpg: marginals needed: 3  completes needed: 1  trust model: pgp
gpg: Tiefe: 0  gültig:   1  signiert:   0  Vertrauen: 0-, 0q, 0n, 0m, 0f, 1u
/home/cweiske/deb.open-dreambox.org/gpg-s3kr1t/pubring.gpg
----------------------------------------------------------
pub   rsa2048 2017-09-22 [SC] [verfallen: 2019-09-22]
      D692A52C97747BBCA5EA7FECC55DC76D15E60BE8
uid        [ verfallen ] deb.open-dreambox.org' <deb@open-dreambox.org>

I changed the expiration date of the public key (secret keys do not expire):

$ gpg --edit-key D692A52C97747BBCA5EA7FECC55DC76D15E60BE8
gpg> expire
Wie lange bleibt der Schlüssel gültig? (0) 1y
Key verfällt am Mi 23 Sep 2020 20:18:56 CEST
Ist dies richtig? (j/N) j
gpg> quit
Änderungen speichern? (j/N) j

Signing now works again.

Written by Christian Weiske.

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