dpkg-source: let --commit create debian/patches when required

Reported-by: Jakub Wilk <jwilk@debian.org>

debian/changelog

@@ -2,6 +2,7 @@ dpkg (1.16.1.1) UNRELEASED; urgency=low
 
   * Fix dpkg-source to not ignore the automatic patch when checking
     for unrecorded changes.
+  * Let dpkg-source --commit create debian/patches when required.
 
  -- Raphaël Hertzog <hertzog@debian.org>  Tue, 27 Sep 2011 08:15:51 +0200
 

scripts/Dpkg/Source/Package/V2.pm

@@ -644,6 +644,7 @@ sub commit {
         $patch_name =~ s/\s+/-/g;
         $patch_name =~ s/\///g;
     }
+    mkpath(File::Spec->catdir($dir, "debian", "patches"));
     my $patch = $self->register_patch($dir, $tmpdiff, $patch_name);
     system("sensible-editor", $patch);
     unlink($tmpdiff) || syserr(_g("cannot remove %s"), $tmpdiff);