LP:737474 - Wrong result with DAY(COALESCE(NULL)) in 5.1-micro

Not repeatable in mysql-5.1

DAY(NULL) is NULL and COALESCE(NULL) is NULL, so DAY(COALESCE(NULL)) should also be NULL. However, 5.1-micro returns 0 instead.

MySQL [test]> select DAY(COALESCE(NULL));
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1 row in set (0.00 sec)