Fix latin-1 handling in webhook header values

hc/api/tests/test_notify_webhook.py

@@ -359,3 +359,21 @@ class NotifyWebhookTestCase(BaseTestCase):
         args, kwargs = mock_request.call_args
 
         self.assertEqual(kwargs["headers"]["X-Foo"], "bār")
+
+    @patch("hc.api.transports.requests.request")
+    def test_webhooks_handle_latin1_in_headers(self, mock_request):
+        definition = {
+            "method_down": "GET",
+            "url_down": "http://foo.com",
+            "headers_down": {"X-Foo": "½"},
+            "body_down": "",
+        }
+
+        self._setup_data(json.dumps(definition))
+        self.check.save()
+
+        self.channel.notify(self.check)
+        args, kwargs = mock_request.call_args
+
+        self.assertEqual(kwargs["headers"]["X-Foo"], "½")
+

hc/api/transports.py

@@ -223,7 +223,7 @@ class Webhook(HttpTransport):
         result = replace(template, ctx)
         if latin1:
             # Replace non-latin-1 characters with XML character references.
-            result = result.encode("latin-1", "xmlcharrefreplace").decode()
+            result = result.encode("latin-1", "xmlcharrefreplace").decode("latin-1")
 
         return result