Bug#6776

  Failure to delete rows from mysql.func table caused by missing
  charset conversion for index read by pk.

sql/sql_udf.cc

@@ -493,8 +493,11 @@ int mysql_drop_function(THD *thd,const LEX_STRING *udf_name)
   tables.real_name= tables.alias= (char*) "func";
   if (!(table = open_ltable(thd,&tables,TL_WRITE)))
     goto err;
-  if (!table->file->index_read_idx(table->record[0],0,(byte*) udf_name->str,
-				   (uint) udf_name->length,
+  table->field[0]->store(udf_name.str, udf_name.length, system_charset_info);
+  table->file->extra(HA_EXTRA_RETRIEVE_ALL_COLS);
+  if (!table->file->index_read_idx(table->record[0], 0,
+				   (byte*) table->field[0]->ptr,
+				   table->key_info[0].key_length
 				   HA_READ_KEY_EXACT))
   {
     int error;