Authorisation failures due to incorrect vhost specified on TLS connections could use better error message

[michaelklishin]

Not sure if we can control this as this may be how Ruby's OpenSSL extension does TLS upgrade, but still.

A user reported that connecting with TLS and incorrectly specific vhost results in

{handshake_error,opening,0,
                {amqp_error,access_refused,
                            "access to vhost '/' refused for user 'upgrade-admin'",
                            'connection.open'}}

RabbitMQ log and

OpenSSL::SSL::SSLError: SSL_connect returned=1 errno=0 state=SSLv2/v3 read server hello A: unknown protocol

from Bunny. We should look into making the message clearer.