diff --git a/xCAT-test/unit/builddebs_release_placeholder.t b/xCAT-test/unit/builddebs_release_placeholder.t
new file mode 100644
index 000000000..1855d2a76
--- /dev/null
+++ b/xCAT-test/unit/builddebs_release_placeholder.t
@@ -0,0 +1,69 @@
+#!/usr/bin/env perl
+use strict;
+use warnings;
+
+use File::Spec;
+use File::Temp qw(tempdir);
+use FindBin;
+use lib "$FindBin::Bin/../../build-utils/lib";
+use Test::More;
+use XCAT::BuildUtils qw(read_line snap_release);
+
+# builddebs.pl takes the Release file as authoritative. The tracked file holds the
+# placeholder snap000000000000, and buildrpms.pl overwrites it with the commit time.
+# A pipeline that builds only the Genesis debs never runs buildrpms.pl, so the
+# placeholder stays and every deb carries the same version forever.
+#
+# The release decision is extracted from builddebs.pl and run here, so the assertions
+# measure the shipped code rather than a copy of it.
+
+my $repo_root = File::Spec->rel2abs( File::Spec->catdir( $FindBin::Bin, '..', '..' ) );
+my $builder = File::Spec->catfile( $repo_root, 'builddebs.pl' );
+plan skip_all => "builddebs.pl not found" unless -f $builder;
+
+my $src = do { local $/; open my $fh, '<', $builder or die $!; <$fh> };
+
+# BAIL_OUT rather than skip: a rewrite that stops this matching must fail loudly
+# instead of silently covering nothing.
+my ($block) = $src =~ /^(my \$FILE_RELEASE\b.*?^my \$RELEASE\s*=.*?;\n)/ms;
+BAIL_OUT('could not extract the release decision from builddebs.pl')
+    unless defined $block;
+
+my $dir = tempdir( CLEANUP => 1 );
+my $run = 0;
+
+# Resolve the release the way builddebs.pl does, for one Release file content and one
+# --release option. Returns the release string.
+sub release_for {
+    my ( $file_content, $opt_release ) = @_;
+    $run++;
+    my $ROOT = File::Spec->catdir( $dir, "run$run" );
+    mkdir $ROOT or die $!;
+    if ( defined $file_content ) {
+        open( my $fh, '>', File::Spec->catfile( $ROOT, 'Release' ) ) or die $!;
+        print {$fh} $file_content;
+        close($fh);
+    }
+    my $EPOCH = 1756000000;
+    my %opts;
+    $opts{release} = $opt_release if defined $opt_release;
+    my $got = eval "$block\n\$RELEASE";
+    die $@ if $@;
+    return $got;
+}
+
+my $from_epoch = snap_release(1756000000);
+
+is( release_for("snap000000000000\n"), $from_epoch,
+    'the tracked placeholder is not a release, so the commit time is used' );
+
+is( release_for("snap202608240826\n"), 'snap202608240826',
+    'a release buildrpms.pl wrote is still authoritative' );
+
+is( release_for(undef), $from_epoch,
+    'no Release file gives the commit time' );
+
+is( release_for( "snap000000000000\n", 'snap209901010000' ), 'snap209901010000',
+    '--release still wins over the placeholder' );
+
+done_testing();