http: bugfix appendlist method not setting headers if first time

--HG--
extra : convert_revision : svn%3Ab85faa78-f9eb-468e-a121-7cced6da292c%401075

scrapy/trunk/scrapy/http/headers.py

@@ -51,7 +51,9 @@ class Headers(CaselessDict):
         self.setdefault(key, default_list)
 
     def appendlist(self, key, value):
-        self.getlist(key).extend(self.normvalue(value))
+        lst = self.getlist(key)
+        lst.extend(self.normvalue(value))
+        self[key] = lst
 
     def items(self):
         return list(self.iteritems())

scrapy/trunk/scrapy/tests/test_http_headers.py

@@ -87,6 +87,11 @@ class HeadersTest(unittest.TestCase):
         h1.appendlist('header1', 'value3')
         self.assertEqual(h1.getlist('header1'), ['value1', 'value3'])
 
+        h1 = Headers()
+        h1.appendlist('header1', 'value1')
+        h1.appendlist('header1', 'value3')
+        self.assertEqual(h1.getlist('header1'), ['value1', 'value3'])
+
     def test_setlist(self):
         h1 = Headers({'header1': 'value1'})
         self.assertEqual(h1.getlist('header1'), ['value1'])