fix update profile Object id

use synthetic URL with #update-[timestamp] fragment, not just home page URL

tests/test_webmention.py

@@ -1101,10 +1101,11 @@ class WebmentionTest(testutil.TestCase):
             self.req('https://orig/'),
         ))
 
+        id = 'https://orig/#update-2022-01-02T03:04:05+00:00'
         self.assert_deliveries(mock_post, ('https://shared/inbox', 'https://inbox'), {
             '@context': 'https://www.w3.org/ns/activitystreams',
             'type': 'Update',
-            'id': 'http://localhost/r/https://orig/#update-2022-01-02T03:04:05+00:00',
+            'id': f'http://localhost/r/{id}',
             'actor': 'http://localhost/orig',
             'object': {
                 **ACTOR_AS2_FULL,
@@ -1114,12 +1115,12 @@ class WebmentionTest(testutil.TestCase):
         })
 
         expected_as1 = {
-            'id': 'https://orig/#update-2022-01-02T03:04:05+00:00',
+            'id': id,
             'objectType': 'activity',
             'verb': 'update',
             'object': ACTOR_AS1_UNWRAPPED,
         }
-        self.assert_object(f'https://orig/',
+        self.assert_object(id,
                            domains=['orig'],
                            source_protocol='webmention',
                            status='complete',

webmention.py

@@ -138,7 +138,8 @@ class Webmention(View):
         log_data = True
 
         type = as1.object_type(self.source_as1)
-        obj = Object.get_by_id(self.source_url)
+        obj_id = self.source_as1.get('id') or self.source_url
+        obj = Object.get_by_id(obj_id)
         changed = False
 
         if obj:
@@ -158,7 +159,7 @@ class Webmention(View):
                     logger.info(f'Content has changed from last time at {obj.updated}! Redelivering to all inboxes: {obj.undelivered}')
 
         else:
-            obj = Object(id=self.source_url, delivered=[], failed=[],
+            obj = Object(id=obj_id, delivered=[], failed=[],
                          undelivered=[Target(uri=uri, protocol='activitypub')
                                       for uri in inboxes_to_targets.keys()],
                          status='in progress')