Test how a message signed by a revoked key is displayed in our system.

[rrrooommmaaa]

Test all the possible edge cases, e.g.

1. the message is signed by both revoked and non-revoked key.
   1a) We only know the revoked key, but we can lookup a non-revoked key
   1b) We know both keys
   ... etc.
   Current simplified implementation (after PR Verify message by sender #4144) may wrongly display "bad signature" or "missing pubkey" messages.
   I'm leaving a reference to this issue in the relevant piece of code