pass close reason to close() method of new DupeFilter

scrapy/core/scheduler.py

@@ -39,7 +39,7 @@ class Scheduler(object):
             prios = self.dqs.close()
             with open(join(self.dqdir, 'active.json'), 'w') as f:
                 json.dump(prios, f)
-        return self.df.close()
+        return self.df.close(reason)
 
     def enqueue_request(self, request):
         if not request.dont_filter and self.df.request_seen(request):

scrapy/dupefilter.py

@@ -15,7 +15,7 @@ class BaseDupeFilter(object):
     def open(self):  # can return deferred
         pass
 
-    def close(self): # can return a deferred
+    def close(self, reason): # can return a deferred
         pass
 
 
@@ -41,6 +41,6 @@ class RFPDupeFilter(BaseDupeFilter):
         if self.file:
             self.file.write(fp + os.linesep)
 
-    def close(self):
+    def close(self, reason):
         if self.file:
             self.file.close()