check most specific interface first (IStreamIterator before IUnboundStreamIterator)

src/ZPublisher/WSGIPublisher.py

@@ -137,12 +137,12 @@ class WSGIResponse(HTTPResponse):
             body.seek(0)
             self.setHeader('Content-Length', '%d' % length)
             self.body = body
-        elif IUnboundStreamIterator.providedBy(body):
+        elif IStreamIterator.providedBy(body):
             self.body = body
-            self._streaming = 1
             HTTPResponse.setBody(self, '', title, is_error)
-        elif IStreamIterator.providedBy(body):
+        elif IUnboundStreamIterator.providedBy(body):
             self.body = body
+            self._streaming = 1
             HTTPResponse.setBody(self, '', title, is_error)
         else:
             HTTPResponse.setBody(self, body, title, is_error)

src/ZPublisher/tests/test_WSGIPublisher.py

@@ -157,6 +157,7 @@ class WSGIResponseTests(unittest.TestCase):
         response.setBody(body)
         response.finalize()
         self.assertTrue(body is response.body)
+        self.assertEqual(response._streaming, 1)
 
     def test_setBody_IStreamIterator(self):
         from ZPublisher.Iterators import IStreamIterator
@@ -182,6 +183,7 @@ class WSGIResponseTests(unittest.TestCase):
         response.setBody(body)
         response.finalize()
         self.assertTrue(body is response.body)
+        self.assertEqual(response._streaming, 0)
 
     #def test___str__already_wrote_not_chunking(self):
     #    response = self._makeOne()