Fixup unit test

tests/util/test_stream_change_cache.py

@@ -141,8 +141,8 @@ class StreamChangeCacheTests(unittest.TestCase):
         )
 
         # Query all the entries mid-way through the stream, but include one
-        # that doesn't exist in it. We should get back the one that doesn't
-        # exist, too.
+        # that doesn't exist in it. We shouldn't get back the one that doesn't
+        # exist.
         self.assertEqual(
             cache.get_entities_changed(
                 [
@@ -153,7 +153,7 @@ class StreamChangeCacheTests(unittest.TestCase):
                 ],
                 stream_pos=2,
             ),
-            set(["bar@baz.net", "user@elsewhere.org", "not@here.website"]),
+            set(["bar@baz.net", "user@elsewhere.org"]),
         )
 
         # Query all the entries, but before the first known point. We will get