Bug #49910: Behavioural change in SELECT/WHERE on YEAR(4) data type                                  
(Original patch by Sinisa Milivojevic)

The YEAR(4) value of 2000 was equal to the "bad" YEAR(4) value of 0000.                              

The get_year_value() function has been modified to not adjust bad                                    
YEAR(4) value to 2000.