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

3 files changed, 12 insertions, 3 deletions

diff --git a/debian/changelog b/debian/changelog
index 19e372a4..9c0abb3f 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -8,6 +8,9 @@ debhelper (7.2.0) UNRELEASED; urgency=low
     than the old method.
   * Remove rules.simple example, there's no need to use explcit targets
     with dh anymore.
+  * dh: Support debian/rules calling make with -B,
+    which is useful to avoid issues with phony implicit
+    rules (see bug #509756).
 
  -- Joey Hess <joeyh@debian.org>  Thu, 25 Dec 2008 16:26:36 -0500
 
diff --git a/debian/rules b/debian/rules
index 03db2d00..ae141867 100755
--- a/debian/rules
+++ b/debian/rules
@@ -1,4 +1,4 @@
-#!/usr/bin/make -f
+#!/usr/bin/make -Bf
 # If you're looking for an example debian/rules that uses debhelper, see
 # the examples directory.
 # 
@@ -11,3 +11,5 @@
 # Not intended for use by anyone except the author.
 announcedir:
 	@echo ${HOME}/src/joeywiki/code/debhelper/news
+
+.PHONY: build
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}};