dpkg-source: ensure quilt's .pc directory is created before writing .pc/applied-patches

The quilt .pc directory was not created when a new automatic patch
was registered and when no other patches were managed by quilt.

Based-on-patch-by: Tommi Vainikainen <thv+debian@iki.fi>

debian/changelog

@@ -1,3 +1,12 @@
+dpkg (1.15.5.6) UNRELEASED; urgency=low
+
+  * dpkg-source: with format "3.0 (quilt)" ensure quilt's .pc directory is
+    created before trying to register a new patch in .pc/applied-patches.
+    Thanks to Tommi Vainikainen <thv+debian@iki.fi> for the report and the
+    patch.
+
+ -- Raphael Hertzog <hertzog@debian.org>  Wed, 23 Dec 2009 17:05:43 +0100
+
 dpkg (1.15.5.5) unstable; urgency=low
 
   * Allow again new lines in dpkg-source and dpkg-genchanges on substvar and

scripts/Dpkg/Source/Package/V3/quilt.pm

@@ -296,6 +296,7 @@ sub register_autopatch {
     my $patch = File::Spec->catfile($dir, "debian", "patches", $auto_patch);
 
     if (-e $patch) {
+        $self->create_quilt_db($dir);
         # Add auto_patch to series file
         if (not $has_patch) {
             add_line($series, $auto_patch);