Comment 9 for bug 1910432

Validated for Focal according to test case from description:
root@focal-vm:~# dpkg -l | grep dirmngr
ii dirmngr 2.2.19-3ubuntu2.1 amd64 GNU privacy guard - network certificate management service
root@focal-vm:~# apt-key adv --fetch-keys https://www.postgreSQL.org/media/keys/ACCC4CF8.asc
Executing: /tmp/apt-key-gpghome.W9r6hkIT5Y/gpg.1.sh --fetch-keys https://www.postgreSQL.org/media/keys/ACCC4CF8.asc
gpg: requesting key from 'https://www.postgreSQL.org/media/keys/ACCC4CF8.asc'
gpg: key 7FCC7D46ACCC4CF8: public key "PostgreSQL Debian Repository" imported
gpg: Total number processed: 1
gpg: imported: 1
root@focal-vm:~# grep ipv6.disable /proc/cmdline
BOOT_IMAGE=/boot/vmlinuz-5.4.0-65-generic root=UUID=ef66e66c-66c8-47d5-9310-b49fc053c8fe ro ipv6.disable=1 quiet splash console=tty1 console=ttyS0 vt.handoff=7

I also ran a simple test with v4/v6 exclusive connections as well as a dual
stack connection, to make sure we didn't introduce any major regressions:
root@focal-vm:~# apt-key adv --fetch-keys https://ipv4.google.com
Executing: /tmp/apt-key-gpghome.VV7UHTmUDt/gpg.1.sh --fetch-keys https://ipv4.google.com
gpg: requesting key from 'https://ipv4.google.com'
gpg: no valid OpenPGP data found.
gpg: Total number processed: 0
root@focal-vm:~# apt-key adv --fetch-keys https://ipv6.google.com
Executing: /tmp/apt-key-gpghome.OiPpZl0mQm/gpg.1.sh --fetch-keys https://ipv6.google.com
gpg: requesting key from 'https://ipv6.google.com'
gpg: no valid OpenPGP data found.
gpg: Total number processed: 0
root@focal-vm:~# apt-key adv --fetch-keys https://www.postgreSQL.org/media/keys/ACCC4CF8.asc
Executing: /tmp/apt-key-gpghome.a3KNTZlRrM/gpg.1.sh --fetch-keys https://www.postgreSQL.org/media/keys/ACCC4CF8.asc
gpg: requesting key from 'https://www.postgreSQL.org/media/keys/ACCC4CF8.asc'
gpg: key 7FCC7D46ACCC4CF8: "PostgreSQL Debian Repository" not changed
gpg: Total number processed: 1
gpg: unchanged: 1