"malicious" ttype sent from wild, test len(buf)

1984.ws was unresponsive after the following exception.

Looks like somebody did IAB, SB, TTYPE, SE. Perhaps this is
a client's way of saying "I don't know" ? regardless, handle
as a "buf too short" kind of error.

Sun-02-09 12:09PM Debug   telnet.py 779 recv SB: TTYPE array('c')
Traceback (most recent call last):
  File "/usr/lib/python2.7/runpy.py", line 162, in _run_module_as_main
    "__main__", fname, loader, pkg_name)
  File "/usr/lib/python2.7/runpy.py", line 72, in _run_code
    exec code in run_globals
  File "/usr/local/lib/python2.7/dist-packages/x84/engine.py", line 448, in <module>
    exit(main())
  File "/usr/local/lib/python2.7/dist-packages/x84/engine.py", line 71, in main
   _loop(telnetd)
  File "/usr/local/lib/python2.7/dist-packages/x84/engine.py", line 402, in _loop
    telnet_recv(fds)
  File "/usr/local/lib/python2.7/dist-packages/x84/engine.py", line 123, in telnet_recv
    client.socket_recv()
  File "/usr/local/lib/python2.7/dist-packages/x84/telnet.py", line 442, in socket_recv
    self._iac_sniffer(byte)
  File "/usr/local/lib/python2.7/dist-packages/x84/telnet.py", line 488, in _iac_sniffer
    self._two_byte_cmd(byte)
  File "/usr/local/lib/python2.7/dist-packages/x84/telnet.py", line 502, in _two_byte_cmd
    self._sb_decoder()
  File "/usr/local/lib/python2.7/dist-packages/x84/telnet.py", line 783, in _sb_decoder
    elif (TTYPE, IS) == (buf[0], buf[1]):
IndexError: array index out of range

Sun-02-09 12:09PM warn  terminal.py 604 '75.87.187.220:48852' TERM not determined by TTYPE.