Partial fix for problem in SF buf #487458

Partial fix for problem in SF buf #487458

Rev 1.20 introduced a call to getpeername() in the dispatcher
constructor.  This only works for a connected socket.  Apparently
earlier versions of the code worked with un-connected sockets, e.g. a
listening socket.

It's not clear that the code is supposed to accept these sockets,
because it sets self.connected = 1 when passed a socket.  But it's
also not clear that it should be a fatal error to pass a listening
socket.

The solution, for now, is to put a try/except around the getpeername()
call and continue if it fails.  The self.addr attribute is used
primarily (only?) to produce a nice repr for the object, so it hardly
matters.  If there is a real error on a connected socket, it's likely
that subsequent calls will fail too.