Fix crash when attempting to log failed 'SET NAMES'

Session 'status' and 'client_myds->DSS' should never be modified for a
regular session prior to calling 'RequestEnd'. It's 'RequestEnd'
responsibility to appropriately change these statuses after the rest of
cleanup operations for the request has taken place, including logging.

include/MySQL_Session.h

@@ -130,9 +130,21 @@ class MySQL_Session
 	bool handler_CommitRollback(PtrSize_t *);
 	bool handler_SetAutocommit(PtrSize_t *);
 	/**
-	 * @brief Performs the cleanup of current session state, and the required operations to the supplied
-	 *   'MySQL_Data_Stream' required for processing further queries.
-	 * @param The 'MySQL_Data_Stream' which executed the previous query and which status should be updated.
+	 * @brief Should execute most of the commands executed when a request is finalized.
+	 * @details Cleanup of current session state, and required operations to the supplied 'MySQL_Data_Stream'
+	 *   for further queries processing. Takes care of the following actions:
+	 *   - Update the status of the backend connection (if supplied), with previous query actions.
+	 *   - Log the query for the required statuses.
+	 *   - Cleanup the previous Query_Processor output.
+	 *   - Free the resources of the backend connection (if supplied).
+	 *   - Reset all the required session status flags. E.g:
+	 *       + status
+	 *       + client_myds::DSS
+	 *       + started_sending_data_to_client
+	 *       + previous_hostgroup
+	 *   NOTE: Should become the place to hook other functions.
+	 * @param myds If not null, should point to a MySQL_Data_Stream (backend connection) which connection status
+	 *   should be updated, and previous query resources cleanup.
 	 */
 	void RequestEnd(MySQL_Data_Stream *);
 	void LogQuery(MySQL_Data_Stream *);

lib/MySQL_Session.cpp

@@ -2480,8 +2480,6 @@ bool MySQL_Session::handler_again___status_CHANGING_CHARSET(int *_rc) {
 				client_myds->myprot.generate_pkt_ERR(true,NULL,NULL,1,mysql_errno(myconn->mysql),sqlstate,mysql_error(myconn->mysql));
 				myds->destroy_MySQL_Connection_From_Pool(true);
 				myds->fd=0;
-				status=WAITING_CLIENT_DATA;
-				client_myds->DSS=STATE_SLEEP;
 				RequestEnd(myds);
 			}
 		} else {
@@ -7466,8 +7464,6 @@ void MySQL_Session::LogQuery(MySQL_Data_Stream *myds) {
 		}
 	}
 }
-// this should execute most of the commands executed when a request is finalized
-// this should become the place to hook other functions
 void MySQL_Session::RequestEnd(MySQL_Data_Stream *myds) {
 	// check if multiplexing needs to be disabled
 	char *qdt = NULL;