Minor bugfixes in pop client code.

* libproto/pop/pop3_carrier.c (mu_pop3_set_carrier): Switch to
MU_POP3_CONNECT state.
* libproto/pop/pop3_disconnect.c (mu_pop3_disconnect): Check if
the stream is actually open before trying to close it.

@@ -42,6 +42,7 @@ mu_pop3_set_carrier (mu_pop3_t pop3, mu_stream_t carrier)
   pop3->carrier = carrier;
   if (MU_POP3_FISSET (pop3, MU_POP3_TRACE))
     _mu_pop3_trace_enable (pop3);
+  pop3->state = MU_POP3_CONNECT;
   return 0;
 }
 

@@ -49,5 +49,7 @@ mu_pop3_disconnect (mu_pop3_t pop3)
     }
 
   /* Close the stream.  */
+  if (mu_stream_is_open (pop3->carrier))
     return mu_stream_close (pop3->carrier);
+  return 0;
 }