Fix a logic error in connection_tls_continue_handshake().
(If we take the branch above this assertion, than we *didn't* have a
v1 handshake. So if we don't take the branch, we did. So if we
reach this assertion, we must be running as a server, since clients
no longer attempt v1 handshakes.)
Fix for bug 17654; bugfix on 9d019a7db725dca3dfdbf8d4dbc3b51835e0b49e.
Bug not in any released Tor.