When executing the init_connect statement, thd->net.vio is set to 0, to         
forbid sending any results to the client. As a side effect we don't log         
possible errors, either.                                                        
                                                                                
Now we write warnings to the error log if an init_connect query                
fails.                                                                          


sql/sql_parse.cc:
  Fix for bug #22158: Errors in init_connect terminate connections silently
  - raise warnings if the init_connect execution fails.