fix(xcat-dep): drop a deb that fails its smoke

The debs land in staging before the smoke runs, and the publish gate checks
names and versions only. A deb whose binary could not run therefore stayed in
staging and was eligible for publication, which is the case the smoke exists to
catch. The failure now removes the debs it rejected and says so.

BuildUtils.pm

@@ -801,7 +801,17 @@ sub build_deb_in_chroot {
     die "[$pkg] build succeeded in the chroot but no .deb is visible at $a{result_dir} on the host\n"
       . "  (is --result-dir on a path bind-mounted into the chroot, e.g. under /opt/xcat-ci-shared?)\n"
       unless @debs;
-    smoke_deb_in_chroot(%a, debs => \@debs) if $a{smoke};
+    if ($a{smoke}) {
+        # The debs are already in staging, and the publish gate checks names and versions, not
+        # whether the binary runs. A deb that fails the smoke must not survive the failure, or the
+        # next publish ships exactly the broken binary the smoke exists to catch.
+        my $ok = eval { smoke_deb_in_chroot(%a, debs => \@debs); 1 };
+        unless ($ok) {
+            my $err = $@ || "unknown smoke failure\n";
+            unlink @debs;
+            die $err . "[$pkg] the debs were removed from $a{result_dir}: they did not pass the smoke\n";
+        }
+    }
     print "[$pkg] OK (" . scalar(@debs) . " deb(s) in $a{result_dir})\n";
     return scalar @debs;
 }