Downloading: http://repo.aptly.info/system-tests/archive.debian.org/debian-archive/debian/dists/stretch/InRelease
Error (retrying): HTTP code 404 while fetching http://repo.aptly.info/system-tests/archive.debian.org/debian-archive/debian/dists/stretch/InRelease
Retrying 0 http://repo.aptly.info/system-tests/archive.debian.org/debian-archive/debian/dists/stretch/InRelease...
Download Error: http://repo.aptly.info/system-tests/archive.debian.org/debian-archive/debian/dists/stretch/InRelease
Downloading: http://repo.aptly.info/system-tests/archive.debian.org/debian-archive/debian/dists/stretch/Release
Downloading: http://repo.aptly.info/system-tests/archive.debian.org/debian-archive/debian/dists/stretch/Release.gpg

gpgv: Signature made Sat Aug 14 07:43:24 2021 UTC
gpgv:                using RSA key 16E90B3FDF65EDE3AA7F323C04EE7237B7D453EC

gpgv: Signature made Sat Aug 14 07:43:25 2021 UTC
gpgv:                using RSA key 0146DC6D4A0B2914BDED34DB648ACFD622F3D138

gpgv: Signature made Sat Aug 14 08:46:19 2021 UTC
gpgv:                using RSA key A7236886F3CCCAAD148A27F80E98404D386FA1D9

gpgv: Signature made Sat Aug 14 08:26:43 2021 UTC
gpgv:                using RSA key 067E3C456BAE240ACEE88F6FEF0F382A1A7B6500
gpgv:                issuer "debian-release@lists.debian.org"

ERROR: unable to fetch mirror: verification of detached signature failed: exit status 2