Shouldn't the v3 client process the certs cell before sending her netinfo cell?

The tor-spec used to say:

   As soon as it gets the CERTS cell, the initiator knows
   whether the responder is correctly authenticated.  At this point the
   initiator may send a NETINFO cell if it does not wish to
   authenticate, or a CERTS cell, an AUTHENTICATE cell (4.4), and a NETINFO
   cell if it does.

I changed it to:

   The initiator can use the CERTS cell to confirm whether
   the responder is correctly authenticated. If the initiator does not wish
   to authenticate, it can send a NETINFO cell once it has received the
   VERSIONS cell from the responder. If the initiator does wish to
   authenticate, it waits until it gets the AUTH_CHALLENGE cell, and then
   sends a CERTS cell, an AUTHENTICATE cell (4.4), and a NETINFO
   cell.

since that's what the code does.

But troll_un points out that we should probably change the code so the client checks the CERTS cell and either hangs up then, or sends her NETINFO comfortable in the knowledge that she knows who she's sending the NETINFO cell to.

If we do change the code, we'd then want to revert (and probably still clean up a bit more) the spec change.