send an ALERT-messages immediately if decryption of the session key
failes. Continue handshaking as if nothing is wrong.

Either some other invalid message is recieved, and handshaking failes
at that time, or the client sends a change cipher message, followed by
a completely garbled finished-message (as the server and client will
not be using the same keys), or the client will wait for ever for an
answer.

Rev: lib/modules/SSL.pmod/handshake.pike:1.9