test no-op options and print info message when they are used

coverage.sh

@@ -549,6 +549,22 @@ else
 	./run_null.sh SUDO
 fi
 
+print_header "mode=root,variant=apt: debootstrap no-op options"
+cat << END > shared/test.sh
+#!/bin/sh
+set -eu
+export LC_ALL=C.UTF-8
+$CMD --mode=root --variant=apt --resolve-deps --merged-usr --no-merged-usr unstable /tmp/debian-unstable $mirror
+tar -C /tmp/debian-unstable --one-file-system -c . | tar -t | sort > tar2.txt
+diff -u tar1.txt tar2.txt
+rm -r /tmp/debian-unstable
+END
+if [ "$HAVE_QEMU" = "yes" ]; then
+	./run_qemu.sh
+else
+	./run_null.sh SUDO
+fi
+
 # test all variants
 
 for variant in essential apt required minbase buildd important debootstrap - standard; do

mmdebstrap

@@ -1662,6 +1662,7 @@ sub main() {
 	mode => 'auto',
 	dpkgopts => [],
 	aptopts => [],
+	noop => [],
 	customize => [],
     };
     chomp ($options->{architectures} = `dpkg --print-architecture`);
@@ -1681,13 +1682,17 @@ sub main() {
 	'debug' => sub { $verbosity_level = 3; },
 	# no-op options so that mmdebstrap can be used with
 	# sbuild-createchroot --debootstrap=mmdebstrap
-	'resolve-deps' => sub {},
-	'merged-usr' => sub {},
-	'no-merged-usr' => sub {},
+	'resolve-deps' => sub { push @{$options->{noop}}, 'resolve-deps'; },
+	'merged-usr' => sub { push @{$options->{noop}}, 'merged-usr'; },
+	'no-merged-usr' => sub { push @{$options->{noop}}, 'no-merged-usr'; },
 	# option is hidden until I'm happy with it
 	'customize=s@' => \$options->{customize},
     ) or pod2usage(-exitval => 2, -verbose => 1);
 
+    foreach my $arg (@{$options->{noop}}) {
+	info "The option --$arg is a no-op. It only exists for compatibility with some debootstrap wrappers.";
+    }
+
     my @valid_variants = ('extract', 'custom', 'essential', 'apt', 'required',
 	'minbase', 'buildd', 'important', 'debootstrap', '-', 'standard');
     if (none { $_ eq $options->{variant}} @valid_variants) {