Empty field gets set to 0 when updating bug

[Tosh, Michael J]

Quoting Andrew Marold:
> When I edit a bug if I leave this field
> empty, it winds up getting set to 0. If I set it to some valid valid
> it gets set properly. 

What is the default value for this field, and is Null set to YES?
(Mysql: describe bugs;)

> On a related note, where are you supposed to put validators for new
> fields ? I tried putting some code in run_create_validators() but it
> didn't appear to be getting used. This particular field is never set
> on bug creation, only on subsequent updates.

sub VALIDATORS returns an hash of callback functions indexed by the
fields they are used to validate.  (In bugzilla 3.0.x anyway...)