sombrero's fake HttpRequest for ACTIVITY_GET requests supplies an Accept header.

Otherwise it doesn't get routed to the right view now that we route based on Accept.

kepi/sombrero_sendpub/fetch.py

@@ -127,6 +127,10 @@ def _fetch_local_by_url(address, wanted):
         as an ACTIVITY_GET method.
         """
 
+        headers = {
+                'Accept': 'application/activity+json',
+                }
+
         def __init__(self, path):
             super().__init__()