Bug 40005: Discard dannenberg from missing_authorities

Until tor#40128 is solved there is not much the operator of dannenberg
can do.

consensus_health_checker.py

 #!/usr/bin/env python
-# Copyright 2013-2019, Damian Johnson and The Tor Project
+# Copyright 2013-2020, Damian Johnson and The Tor Project
 # See LICENSE for licensing information
 
 """
@@ -644,6 +644,8 @@ def has_authority_flag(latest_consensus, consensuses, votes):
 
   known_authorities = set(DIRECTORY_AUTHORITIES.keys())
   missing_authorities = known_authorities.difference(seen_authorities)
+  # Discard dannenberg for now until tor#40128 is solved, see #40005.
+  missing_authorities.discard('dannenberg')
   extra_authorities = seen_authorities.difference(known_authorities)
 
   issues = []