Comment 1 for bug 1879348

This should patch it:

--- /usr/bin/debmirror 2017-07-22 01:09:37.000000000 +0000
+++ ./debmirror 2020-05-19 07:49:07.409643328 +0000
@@ -2679,7 +2679,7 @@
   if ($use_cache) {
     say(": using cache.");
     foreach my $file (sort keys %files) {
- next if (@di_dists && $file =~ m:installer-\w(-|\w)*/current/images/:);
+ next if (@di_dists && $file =~ m:installer-\w(-|\w)*/current/[a-z-]*images/:);
       if ($files{$file} == 2 && -f $file) {
         say("deleting $file") if ($verbose);
         if (! $do_dry_run) {
@@ -2696,7 +2696,7 @@
     foreach my $file (`find . -type f 2>/dev/null`) {
       chomp $file;
       $file=~s:^\./::;
- next if (@di_dists && $file =~ m:installer-\w(-|\w)*/current/images/:);
+ next if (@di_dists && $file =~ m:installer-\w(-|\w)*/current/[a-z-]*images/:);
       unless ((exists $files{$file} &&
                $files{$file} != -1 && $files{$file} != 2) or
               (defined($ignore) && $file=~/$ignore/o)) {
@@ -2764,9 +2764,18 @@

       my $image_dir = "dists/$dist/main/installer-$arch/current/images";
       make_dir ("$tdir/$image_dir");
+ my @old_errlog = @errlog;
+ my $old_num_errors = $num_errors;
       if (!remote_get("$image_dir/MD5SUMS", $tdir)) {
- say("Failed to download $image_dir/MD5SUMS; skipping.");
- return;
+ say("Failed to download $image_dir/MD5SUMS; trying legacy-images.");
+ $image_dir = "dists/$dist/main/installer-$arch/current/legacy-images";
+ make_dir ("$tdir/$image_dir");
+ if (!remote_get("$image_dir/MD5SUMS", $tdir)) {
+ say("Failed to download $image_dir/MD5SUMS; skipping.");
+ return;
+ }
+ @errlog = @old_errlog;
+ $num_errors = $old_num_errors;
       }
       if (-f "$tdir/$image_dir/MD5SUMS") {
         $bytes_to_get += -s _; # As we did not have the size earlier
@@ -2841,7 +2850,7 @@
 sub di_cleanup {
   # Clean up obsolete files
   foreach my $image_dir (`find dists/ -type d -name images 2>/dev/null`) {
- next unless $image_dir =~ m:/installer-\w(-|\w)*/current/images$:;
+ next unless $image_dir =~ m:/installer-\w(-|\w)*/current/[a-z-]*images$:;
     chomp $image_dir;
     chdir("$image_dir") or die "unable to chdir($image_dir): $!\n";
     foreach my $file (`find . -type f 2>/dev/null`) {