diff --git a/xCAT-test/unit/genesis_ubuntu_build_root.t b/xCAT-test/unit/genesis_ubuntu_build_root.t
index bb086b9c6..cf8363b30 100755
--- a/xCAT-test/unit/genesis_ubuntu_build_root.t
+++ b/xCAT-test/unit/genesis_ubuntu_build_root.t
@@ -1,12 +1,11 @@
 #!/usr/bin/env perl
 # The Ubuntu Genesis build root must carry every command the Ubuntu dracut module marks
-# mandatory. dracut_install reports a missing command and returns, so a command the build
-# root does not supply leaves a hole in the image and the build still exits 0.
+# mandatory. dracut_install reports a missing command and returns 0, so a hole in the image
+# does not fail the build.
 #
-# The mandatory list is read by RUNNING the module: module-setup.sh is sourced with
-# dracut_install shadowed, _dracut_install_opt neutralised (its callers are optional by
-# construction), and install() is called. The package list is read by extracting the
-# REQUIRED_PACKAGES assignment from builddeb-genesis-base and evaluating it.
+# The mandatory list comes from RUNNING the module: module-setup.sh is sourced with
+# dracut_install shadowed, _dracut_install_opt neutralised, and install() called. The
+# package list comes from evaluating the REQUIRED_PACKAGES assignment in the build script.
 use strict;
 use warnings;
 
@@ -23,9 +22,8 @@ plan skip_all => 'builddeb-genesis-base not found' unless -f $builder;
 plan skip_all => 'ubuntu module-setup.sh not found' unless -f $module;
 plan tests => 8;
 
-# Commands the Ubuntu dracut module marks mandatory that a minimal Ubuntu server root does
-# NOT already provide, and the package that supplies each one. Every entry here has to be in
-# REQUIRED_PACKAGES or the image ships without the command.
+# Mandatory commands a minimal Ubuntu server root does NOT already provide, and the package
+# that supplies each one.
 my %PACKAGE_FOR = (
     dhclient  => 'isc-dhcp-client',
     ifenslave => 'ifenslave',
@@ -41,19 +39,16 @@ for my $command (sort keys %PACKAGE_FOR) {
        "the build root installs $PACKAGE_FOR{$command}, which provides '$command'");
 }
 
-# doxcat asks dhclient for the provisioning lease. An image without it never gets an address,
-# so the node netboots and never reports in -- the failure this test exists for.
+# doxcat asks dhclient for the provisioning lease.
 ok($mandatory{dhclient} && scalar(grep { $_ eq 'isc-dhcp-client' } @packages),
    'the Genesis image can obtain a DHCP lease');
 
-# dracut_install is silent about a hole, so the payload needs its own gate before it is
-# packaged. This is the EL path's behaviour (xCAT-genesis-base.spec runs the same verifier).
+# dracut_install is silent about a missing command, so the payload needs its own gate.
+# xCAT-genesis-base.spec runs the same verifier on the EL path.
 my $text = do { open my $fh, '<', $builder or die "$builder: $!"; local $/; <$fh> };
 like($text, qr{verify-genesis-payload}, 'builddeb-genesis-base verifies the payload it packages');
 
-# mandatory_commands($module): source the dracut module with dracut_install shadowed, call
-# install(), and return the bare command names it installs unconditionally. Absolute paths are
-# data files, not commands, and are left out.
+# An absolute path in the install() output is a data file, not a command.
 sub mandatory_commands {
     my ($path) = @_;
     my $dir = tempdir(CLEANUP => 1);
@@ -66,29 +61,28 @@ inst_multiple() { :; }
 inst() { :; }
 dpkg-architecture() { echo x86_64-linux-gnu; }
 . '$path'
-# Every caller of _dracut_install_opt is optional by construction: it installs only what the
-# build root already has. Neutralise it AFTER sourcing so it cannot add to the mandatory set.
+# _dracut_install_opt installs only what the build root already has. Neutralise it after
+# sourcing, so its commands stay out of the mandatory set.
 _dracut_install_opt() { :; }
 install
 BASH
     close $fh;
     my @out = qx{bash '$driver' 2>/dev/null};
-    BAIL_OUT("running install() from $path produced nothing") unless @out;
+    die("running install() from $path produced nothing") unless @out;
     my %seen;
     my @names = grep { !$seen{$_}++ } grep { length && !m{^/} } map { chomp; $_ } @out;
-    BAIL_OUT("install() from $path named no bare commands") unless @names;
+    die("install() from $path named no bare commands") unless @names;
     return @names;
 }
 
-# required_packages($path): extract the REQUIRED_PACKAGES assignment from the build script and
-# evaluate it, so the list comes from the value the script actually uses.
+# Evaluate the assignment rather than parse it, so the list is the value the script uses.
 sub required_packages {
     my ($path) = @_;
     my $text = do { open my $fh, '<', $path or die "$path: $!"; local $/; <$fh> };
     my ($block) = $text =~ /^(REQUIRED_PACKAGES="[^"]*")/ms;
-    BAIL_OUT("no REQUIRED_PACKAGES assignment in $path") unless $block;
+    die("no REQUIRED_PACKAGES assignment in $path") unless $block;
     my $out = qx{bash -c 'set -u; $block; printf "%s\\n" \$REQUIRED_PACKAGES' 2>/dev/null};
     my @packages = grep { length } split /\s+/, ($out // '');
-    BAIL_OUT("REQUIRED_PACKAGES in $path evaluated to nothing") unless @packages;
+    die("REQUIRED_PACKAGES in $path evaluated to nothing") unless @packages;
     return @packages;
 }