fix(mockbuild-all): keep rpms of another architecture out of a target's cell

collect_rpms copied every binary rpm a builder produced. The syslinux builder
also produces syslinux, syslinux-extlinux and their debug rpms for the chroot
it runs in, so a forcearch target that builds the noarch boot loaders in the
native x86_64 chroot would have published x86_64 rpms in the riscv64 cell.
The completeness gate checks names and pins only, so it would have passed.

Keep an rpm only when it is noarch or carries the cell's architecture, read
from the rpm header. The rule lives in MockBuildUtils as rpm_in_cell.

MockBuildUtils.pm

@@ -20,7 +20,7 @@ our @EXPORT_OK = qw(
     parse_evr evr_cmp evr_constraint_ok parse_pin rpmkeys_checksig_problem
     rpm_version rpm_release rpm_sigmd5 rpm_is_signed restamp_release_line
     cross_copy_genesis finalize_xcat_dep bump_dep_release_suffix
-    build_mock_uniqueext
+    build_mock_uniqueext rpm_arch rpm_in_cell
 );
 
 # install_deps_packages($os_id): the host packages mockbuild-all.pl needs to run at all, for the
@@ -568,6 +568,32 @@ sub bump_dep_release_suffix {
 # their roots apart, so three concurrent el8/el9/el10 ppc64le goconserver builds race in one root.
 # When the id is too long, keep a readable leading token AND append a short digest of the FULL id, so
 # distinct ids always yield distinct uniqueext regardless of where in the string they differ.
+# rpm_arch($rpm): the architecture of an rpm. The header decides when the file can be read, so a
+# renamed file does not pass for another architecture; a bare file name falls back to its suffix.
+sub rpm_arch {
+    my ($rpm) = @_;
+    return unless defined $rpm;
+    if (-f $rpm) {
+        my $arch = `rpm -qp --qf '%{ARCH}' ${\ sh_quote($rpm)} 2>/dev/null`;
+        chomp $arch;
+        return $arch if $arch ne '';
+    }
+    my ($arch) = $rpm =~ /\.([A-Za-z0-9_]+)\.rpm$/;
+    return $arch;
+}
+
+# rpm_in_cell($rpm, $target_arch): whether an rpm belongs in the repository cell of $target_arch.
+# A noarch builder run in another architecture's chroot (the x86 boot loaders for riscv64) can
+# emit that chroot's native rpms beside the noarch one; only noarch and the cell's own
+# architecture are kept.
+sub rpm_in_cell {
+    my ($rpm, $target_arch) = @_;
+    my $arch = rpm_arch($rpm);
+    return 0 unless defined $arch && defined $target_arch;
+    return 1 if $arch eq 'noarch';
+    return $arch eq $target_arch ? 1 : 0;
+}
+
 sub build_mock_uniqueext {
     my ($run, $seq, $label) = @_;
 

mockbuild-all.pl

@@ -15,7 +15,7 @@ use Parallel::ForkManager;
 use POSIX qw(strftime);
 use FindBin qw($RealBin);
 use lib $RealBin, "$RealBin/lib";
-use MockBuildUtils qw(sh_quote print_step version_matches required_pkgs
+use MockBuildUtils qw(sh_quote print_step version_matches required_pkgs rpm_in_cell
                       install_deps_packages install_deps_command missing_perl_modules
                       read_manifest verify_repo_packages verify_repo_signature verify_rpm_signatures
                       rpm_version rpm_release rpm_sigmd5 restamp_release_line
@@ -848,11 +848,13 @@ print_step('Collect RPM artifacts');
 print "collection roots:\n";
 print "  $_\n" for @collect_roots;
 
-my ($copied, $skipped_src, $missing_roots) = collect_rpms(
+my ($copied, $skipped_src, $missing_roots, $skipped_foreign) = collect_rpms(
     roots    => \@collect_roots,
     dest_dir => $repo_dir,
+    arch     => $arch,
     dry_run  => $dry_run,
 );
+print "skipped $skipped_foreign rpm(s) of another architecture\n" if $skipped_foreign;
 
 # Assert on what this run BUILT, before the Genesis release is added: the release is
 # installed from a verified directory rather than built here, so counting it first would
@@ -1970,11 +1972,13 @@ sub collect_rpms {
     my (%args) = @_;
     my $roots = $args{roots} // [];
     my $dest  = $args{dest_dir} // die "collect_rpms missing dest_dir\n";
+    my $cell_arch = $args{arch} // die "collect_rpms missing arch\n";
     my $is_dry = $args{dry_run} ? 1 : 0;
 
     my %seen;
     my $copied = 0;
     my $skipped_src = 0;
+    my $skipped_foreign = 0;
     my $missing_roots = 0;
 
     for my $root (@{$roots}) {
@@ -2002,6 +2006,10 @@ sub collect_rpms {
             my $base = basename($rpm);
             next if $genesis_release
               && $base =~ /^xCAT-genesis-openembedded-/;
+            if (!rpm_in_cell($rpm, $cell_arch)) {
+                $skipped_foreign++;
+                next;
+            }
             next if $seen{$base}++;
             if ($is_dry) {
                 print "DRY-RUN copy: $rpm -> $dest/$base\n";
@@ -2014,7 +2022,7 @@ sub collect_rpms {
         }
     }
 
-    return ($copied, $skipped_src, $missing_roots);
+    return ($copied, $skipped_src, $missing_roots, $skipped_foreign);
 }
 
 sub collect_srpms {