dh: Support debian/rules calling make with -B

That is useful to avoid issues with phony implicit rules
(see bug #509756).

Apparently make treats the name of the Makfile as an automaticall
set up target, so this causes it to try to build the Makefile
even though it's up-to-date, and the implicit target
makes it run 'dh debian/rules'.

So, make that a no-op.
(cherry picked from commit 378b377ef732119de4c2a08dcb9721500b017da1)

Conflicts:

	debian/changelog
	dh

1 files changed, 6 insertions, 2 deletions

diff --git a/dh b/dh
index 88dc9c4a..571d4b63 100755
--- a/dh
+++ b/dh
@@ -311,8 +311,12 @@ if (! @ARGV) {
 	error "specify a sequence to run";
 }
 my $sequence=shift;
-if (! exists $sequences{$sequence}) {
-	error "Unknown sequence $sequence (chose from: ".
+if ($sequence eq 'debian/rules') {
+	# make -B causes the rules file to be run as a target
+	exit 0
+}	
+elsif (! exists $sequences{$sequence}) {
+	error "Unknown sequence $sequence (choose from: ".
 		join(" ", sort keys %sequences).")";
 }
 my @sequence=@{$sequences{$sequence}};