Fixed a boundary condition error in ftp_readresp() whereby a non-terminal

line of a multiline FTP response whose last byte landed exactly at the end
of the BUFSIZE-length buffer would be treated as the terminal response
line.  The following response code read in would then actually be the
end of the previous response line, and all responses from then on would
correspond to the wrong command. Test case 1062 verifies this.

Stop closing a never-opened ftp socket.