Wrong result for CAST from TIME or DATETIME with zero integer part and non-zero microseconds to DECIMAL(X,Y)

SET sql_mode=''; -- Allow zero date

SELECT

  CAST(TIMESTAMP'0000-00-00 00:00:00.123456' AS DECIMAL(10,6)) AS c1,

  CAST(TIME'00:00:00.123456' AS DECIMAL(10,6)) AS c2;

+----------+----------+

| c1       | c2       |

+----------+----------+

| 0.000000 | 0.000000 |

+----------+----------+