tryton/sao — pull request #1 by slashrod (2014-08-03 13:54:25+00:00)
Title: Check datetime field values before formatting.

Sao.View.Form.DateTime._default = null;
As a consequence, for new records, record.field_get(this.field_name) return null.
However Sao.common.format_time expect a date as value. So format the date only when something truthy has been returned as value.