Comment 3 for bug 1862764

According to https://wiki.debian.org/DebianRepository/UseThirdParty I have to put third-party keys in /usr/share/keyrings, but a command like

add-apt-repository -y "deb [signed-by=/usr/share/keyrings/mykey.gpg] https://my.repo/ impish main"

fails. If I understand correctly, this means that add-apt-repository cannot be used for third-party repos (at least not according to Debian’s security standards).