Update blank custom fields

Found an issue with empty (null) custom fields on update.

The tool works great, thanks. However…the tool will not update custom fields if the previously stored meta value is blank/null. If the custom field has an existing value then the tool will replace the existing value.

I would like the tool to update a custom field to whatever value I give it in the CSV regardless if there is a pre-existing value.

If you could point me in the right direction to make this happen I would be much appreciated.

Much thanks!

http://wordpress.org/plugins/really-simple-csv-importer/