input.Field = old.Field doesn't work when old.Field=null

input.Field = old.Field doesn't work when old.Field=null

Hi Zoho, 

On my "On Edit -> On Validate" I have a script with a rule, in case the rule is not applicable, I'd like to revet to the old data. for this I'm using input.Field = old.Field.
but - on fields when the old version does not have data (null) the input.Field is not updated (say with the new data entered.

Please fix this

Thanks

Ravid