specific to 5.0 version of the patch is motivated by the fact that a wrapper over 
MYSQLLOG::write can not help in 5.0 where query's charset is embedded into event instance in the constructor.


sql/mysql_priv.h:
  this 4.1 specific code does not help in 5.0
sql/sql_base.cc:
  No wrapper similar to 4.1's version is done since Query_log_event constructor
  takes care of encodings in 5.0 whereas log::write method does it in 4.1.
  We can introduce an additional constuctor for Query_log_event to pass desired
  (i.e system_character_info) charset different from THD's version.
  But I am delaying this while there are not more bugs similar to this one reported.