dpkg-source: remove quilt's .pc directory when --unapply-patches is in use

debian/changelog

@@ -73,6 +73,8 @@ dpkg (1.16.0) UNRELEASED; urgency=low
     NFS doesn't introduce any inconsistency. Closes: #613023
     Thanks to Jonathan Nieder <jrnieder@gmail.com> for the patch and the
     diagnosis.
+  * dpkg-source will now remove quilt's .pc directory when --unapply-patches
+    is in use. Closes: #591858
 
   [ Jonathan Nieder ]
   * Remove support for use of synchronous sync(2), due to its pernicious

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

@@ -251,7 +251,7 @@ sub unapply_patches {
                                  '--no-backup-if-mismatch' ]);
         erasedir(File::Spec->catdir($dir, ".pc", $patch));
     }
-    unlink($pc_applied);
+    erasedir(File::Spec->catdir($dir, ".pc"));
 }
 
 sub prepare_build {