diff --git a/xCAT-test/unit/debian_install_boot_files.t b/xCAT-test/unit/debian_install_boot_files.t
index 3bcbcfd31..d866c36b2 100644
--- a/xCAT-test/unit/debian_install_boot_files.t
+++ b/xCAT-test/unit/debian_install_boot_files.t
@@ -7,10 +7,9 @@ use File::Temp qw(tempdir);
 use FindBin;
 use Test::More;
 
-# The installer kernel and initrd sit in a different place on every Ubuntu media layout:
-# netboot trees name them after the Debian architecture, live images keep them under
-# casper, and a hardware-enablement kernel ships beside the release one. Build each layout
-# on disk and ask the resolver, rather than reading the table that describes them.
+# The installer kernel and initrd sit in a different place on every Ubuntu media layout.
+# Build each layout on disk and ask the resolver, rather than read the table that
+# describes them.
 
 use lib "$FindBin::Bin/../../perl-xCAT";
 use lib "$FindBin::Bin/../../xCAT-server/lib/perl";
@@ -103,10 +102,9 @@ is(
     'riscv64 does not accept the kernel name the other live images use',
 );
 
-# The Ubuntu ppc64el live-server ISO carries no netboot tree at all. 22.04 and 24.04 ship
-# casper/hwe-vmlinux + casper/hwe-initrd beside casper/vmlinux + casper/initrd; 26.04 ships
-# the release pair only. Without these entries nodeset stops the diskful install with
-# "The network boot initrd.gz is not found in <pkgdir>/install/netboot".
+# The Ubuntu ppc64el live-server ISO carries no netboot tree. 22.04 and 24.04 ship the
+# hardware-enablement pair under casper beside the release pair; 26.04 ships the release
+# pair only.
 is(
     resolved('ppc64le', 'ppc64el', media('casper/vmlinux', 'casper/initrd')),
     'casper/vmlinux|casper/initrd',
@@ -127,8 +125,7 @@ is(
     'a POWER netboot tree still wins over a live image on the same media',
 );
 
-# mkinstall refused POWER media that carried no install/netboot/initrd.gz, whatever
-# install_boot_files could resolve. One routine answers the question now.
+# mkinstall asks this routine, so it accepts every media install_boot_files resolves.
 can_ok('xCAT_plugin::debian', 'install_media_is_bootable');
 is(
     xCAT_plugin::debian::install_media_is_bootable('ppc64le', 'ppc64el',
diff --git a/xCAT-test/unit/debian_install_prescript.t b/xCAT-test/unit/debian_install_prescript.t
index 9edfde213..db20da711 100644
--- a/xCAT-test/unit/debian_install_prescript.t
+++ b/xCAT-test/unit/debian_install_prescript.t
@@ -10,16 +10,9 @@ use Test::More;
 # early-commands append to /autoinstall.yaml. pre.ubuntu.ppc64 writes a partman recipe
 # for the debian-installer, which is not YAML at all.
 #
-# mkinstall chose the subiquity script, then overwrote that choice for every ppc64
-# node. A ppc64el 24.04 install therefore appended a partman recipe to its
-# autoinstall.yaml, Subiquity failed on the malformed document, the error-commands
-# tarred /var/log/installer and the node rebooted into the installer again -- nine
-# times in build #121 of xcat-core-devel-ubuntu-cd, cell ubuntu-24-ppc64le-devel,
-# case reg_linux_diskfull_installation_flat. The node answered ping from the live
-# installer the whole time, so the case failed on
-# "root@xcat25-cn: Permission denied (publickey,password)".
-#
-# The ppc64 script belongs to the debian-installer path only.
+# mkinstall chose the subiquity script, then overwrote that choice for every ppc64 node,
+# so a ppc64el Subiquity install appended a partman recipe to its autoinstall.yaml. The
+# ppc64 script belongs to the debian-installer path only.
 
 use lib "$FindBin::Bin/../../perl-xCAT";
 use lib "$FindBin::Bin/../../xCAT-server/lib/perl";
@@ -28,7 +21,7 @@ plan skip_all => 'debian.pm not found' unless -r $plugin;
 eval { require $plugin; 1 } or plan skip_all => "could not load debian.pm: $@";
 
 can_ok('xCAT_plugin::debian', 'install_prescript')
-    or BAIL_OUT('mkinstall still chooses the pre-install script inline, so nothing can drive it');
+    or die('mkinstall still chooses the pre-install script inline, so nothing can drive it');
 
 sub chosen {
     my ($platform, $arch, $subiquity) = @_;
diff --git a/xCAT-test/unit/ubuntu_subiquity_storage.t b/xCAT-test/unit/ubuntu_subiquity_storage.t
index a41f1ac4a..7403d41cb 100644
--- a/xCAT-test/unit/ubuntu_subiquity_storage.t
+++ b/xCAT-test/unit/ubuntu_subiquity_storage.t
@@ -31,12 +31,12 @@ is( system("bash -n $pre_path 2>/dev/null"), 0,
 # redirected into a scratch tree. Both substitutions are asserted: if either stops
 # matching, this bails out rather than silently covering nothing or writing to /tmp.
 my ($storage_block) = $script =~ /(^if \[ -d \/sys\/firmware\/efi \]; then\n.*?\n^fi$)/ms;
-BAIL_OUT('the firmware branch that writes the partition file no longer matches')
+die('the firmware branch that writes the partition file no longer matches')
     unless $storage_block;
 
-BAIL_OUT('the firmware test the shadow below answers is gone')
+die('the firmware test the shadow below answers is gone')
     unless $storage_block =~ /\[ -d \/sys\/firmware\/efi \]/;
-BAIL_OUT('the block no longer asks uname for the machine architecture')
+die('the block no longer asks uname for the machine architecture')
     unless $storage_block =~ /uname -m/;
 
 my $sandbox   = File::Temp::tempdir( CLEANUP => 1 );
@@ -46,9 +46,9 @@ my $partfile  = File::Spec->catfile( $sandbox, 'partitionfile' );
 # escapes the sandbox.
 my $branches  = () = $storage_block =~ /^\s*cat <<EOF >\/tmp\/partitionfile$/mg;
 my $rewrites  = ( $storage_block =~ s{/tmp/partitionfile}{$partfile}g );
-BAIL_OUT("the block writes the partition file in $branches places and $rewrites were rewritten")
+die("the block writes the partition file in $branches places and $rewrites were rewritten")
     unless $branches >= 2 && $rewrites == $branches;
-BAIL_OUT('a partition-file path escaped the sandbox')
+die('a partition-file path escaped the sandbox')
     if $storage_block =~ m{/tmp/partitionfile};
 
 my %YAML_FOR;
@@ -66,8 +66,7 @@ sub partition_config_for {
 INSTALL_DISK=/dev/sdz
 logger() { :; }
 uname() { builtin echo $machine; }
-# `[` is shadowed only for the firmware probe; every other test runs unmodified,
-# so the architecture branch is taken by the block's own comparison.
+# Only the firmware probe is answered here; every other test falls through to the builtin.
 [() {
   case "\$1 \$2" in
     "-d /sys/firmware/efi") return @{[ $firmware eq 'uefi' ? 0 : 1 ]} ;;
@@ -80,9 +79,9 @@ SHELL
 
     unlink $partfile;
     system( 'bash', $script ) == 0
-        or BAIL_OUT("the extracted partitioning block failed to run for $firmware");
+        or die("the extracted partitioning block failed to run for $firmware");
     open( my $out_fh, '<', $partfile )
-        or BAIL_OUT("the partitioning block wrote no file for $firmware: $!");
+        or die("the partitioning block wrote no file for $firmware: $!");
     my $yaml = do { local $/; <$out_fh> };
     close($out_fh);
     $YAML_FOR{$firmware} = $yaml;