Comment 0 for bug 1879348

If you use debmirror to mirror the focal repository, and use `--di-dist focal --di-arch=arches`, then the mirroring process fails, because it expects to fetch files from http://archive.ubuntu.com/ubuntu/dists/focal/main/installer-amd64/current/images/ but that does not exist. Instead there is http://archive.ubuntu.com/ubuntu/dists/focal/main/installer-amd64/current/legacy-images/.

$ --host archive.ubuntu.com --method http --rsync-extra=none --diff=none --root ubuntu --keyring /usr/share/keyrings/ubuntu-archive-keyring.gpg --arch amd64 --dist focal --section main,restricted,main/debian-installer,restricted/debian-installer,universe/debian-installer,multiverse/debian-installer --di-dist focal --di-arch=arches --progress --verbose --debug /home/syseleven/dm
...
/usr/bin/debmirror: Created directory: .temp/d-i/
/usr/bin/debmirror: Created directory: .temp/d-i/dists/
/usr/bin/debmirror: Created directory: .temp/d-i/dists/focal/
/usr/bin/debmirror: Created directory: .temp/d-i/dists/focal/main/
/usr/bin/debmirror: Created directory: .temp/d-i/dists/focal/main/installer-amd64/
/usr/bin/debmirror: Created directory: .temp/d-i/dists/focal/main/installer-amd64/current/
/usr/bin/debmirror: Created directory: .temp/d-i/dists/focal/main/installer-amd64/current/images/
http://archive.ubuntu.com/ubuntu/dists/focal/main/installer-amd64/current/images/MD5SUMS => [ 3%] Getting: dists/focal/main/installer-amd64/current/images/MD5SUMS... #** GET http://archive.ubuntu.com/ubuntu/dists/focal/main/installer-amd64/current/images/MD5SUMS ==> 404 Not Found
404 Not Found
failed 404 Not Found
Failed to download dists/focal/main/installer-amd64/current/images/MD5SUMS; skipping.
Errors:
 Download of dists/focal/main/installer-amd64/current/images/MD5SUMS failed: 404 Not Found
Failed to download some Package, Sources or Release files!
WARNING: releasing 1 pending lock...

Also, it is quite annoying that you can't specify `--dist bionic,focal-updates,focal-security,focal-backports`. It will fail because these distributions don't exist yet. However, at some point they wull probably exist, but you won't mirror them.