Ensure that foreign-arch multiarch multistraps work force_unpack was not considering architecture when de-duping the package list (This manifested when doing a foreign-arch multistrap which was also multiarch - i.e. two foreign arches relative to the build arch).

multistrap

@@ -572,16 +572,17 @@ sub force_unpack {
 		my $escaped_path = shellescape("${dir}${cachedir}archives/$deb");
 		my $version = `LC_ALL=C dpkg -f $escaped_path Version`;
 		my $package = `LC_ALL=C dpkg -f $escaped_path Package`;
+		my $arch = `LC_ALL=C dpkg -f $escaped_path Architecture`;
 		chomp ($version);
 		chomp ($package);
 		if (exists $unpack{$package}) {
-			my $test=system("dpkg --compare-versions ". shellescape($unpack{$package}) . " '<<' " . shellescape($version));
+			my $test=system("dpkg --compare-versions ". shellescape($unpack{$package.$arch}) . " '<<' " . shellescape($version));
 			$test >>= 8;
 			# unlink version in $unpack if 0
 			# unlink $deb (current one) if 1
 			if ($test == 0) {
 				my $old = $deb;
-				$old =~ s/$version/$unpack{$package}/;
+				$old =~ s/$version/$unpack{$package.$arch}/;
 				printf (_g("I: Removing %s\n"), $old);
 				unlink "${dir}${cachedir}archives/$old";
 				next;
@@ -590,7 +591,7 @@ sub force_unpack {
 				unlink "${dir}${cachedir}archives/$deb";
 			}
 		}
-		$unpack{$package}=$version;
+		$unpack{$package.$arch}=$version;
 	}
 	if (not @limits) {
 		open (LOCK, ">${dir}${libdir}lists/lock");