Wrong date should not be accepted

When you write a bad date such as "42/14/2012" in a date field in an object, the wiki silently changes it to a valid date, which does not make any sense.

What should happen: a message says to the user that the date he wrote is bad.

Steps to reproduce :

1/ Create a class called "MyTests.TestClass".
2/ Add a "mydate" field of type "Date", with default Date format "dd/MM/yyyy" (but the bug happens with all date formats).
3/ Create a page class "MyTests.DateTest".
4/ Go to object edit mode, and add an object of type "MyTests.TestClass".
5/ Inside your new object, set the "mydate" field to this value: "42/14/2012" or any else bad date. Save.
6/ Go back to the object editor, and see that the bad date was converted to a valid date.