select list widget input normalized twice with node_import

I ran into a problem with node_import and tracked it down to date_selector_make_dbdate() in date.inc. When previewing the imported nodes, the $array argument to this function is actually a properly formatted ISO date string, not an array. This is necessarily the case because node_import allows the user to submit anything which strtotime() can parse, and uses the date module functions themselves to ensure the input is valid before calling node_view() to preview the imported data.

The problem is that node_view invokes date's date_widget() because nodes are shown in preview mode, with no nid present in the node object. With text field date fields, this is not a problem, since date_text_make_dbdate() effectively sees that the input is already a valid ISO date and returns it. However, date_selector_make_dbdate() assumes the field is an array, and if given a valid ISO date as input returns an empty date, thus dropping the date field from the imported content.

There are obviously several places where this could be averted, but I believe the most robust in terms of making the date APIs easy to use from other modules which programmatically create nodes would be to check in date_selector_make_dbdate() for input which is already a valid date, and in that case make no changes.