fix 333877 100% cpu usage on imap idle when connection dies, original idea by robin.grindley@ieee.org, sr=mscott

mailnews/imap/src/nsImapServerResponseParser.cpp

@@ -297,6 +297,8 @@ void nsImapServerResponseParser::ParseIMAPServerResponse(const char *currentComm
       }
     }
   }
+  else
+    SetConnected(PR_FALSE);
   PL_strfree(copyCurrentCommand);
 }