Merge pull request #28705 from cachedout/tornado_http_headers

Account for new headers class in tornado 4.3

salt/netapi/rest_tornado/saltnado.py

@@ -1608,7 +1608,12 @@ class WebhookSaltAPIHandler(SaltAPIHandler):  # pylint: disable=W0223
 
         ret = self.event.fire_event({
             'post': self.raw_data,
-            'headers': self.request.headers,
+            # In Tornado >= v4.0.3, the headers come
+            # back as an HTTPHeaders instance, which
+            # is a dictionary. We must cast this as
+            # a dictionary in order for msgpack to
+            # serialize it.
+            'headers': dict(self.request.headers),
         }, tag)
 
         self.write(self.serialize({'success': ret}))