Code review comment for lp:~spiv/bzr/hpss-log-noise

The fix has two simple parts:

 * don't log UnknownSmartMethod exceptions from the request handler, as these
   are not exceptional (or particularly interesting) events for the server.

 * don't bother trying to invoke do_chunk or do_end if there is no live command
   in the request handler (e.g. because the request we are parsing is currently
   for an unknown method). Unknown requests should simply be consumed and
   discarded (after sending an UnknownMethod response, of course).

This fixes bug #338561.

-Andrew.