Importing records using the merge function deletes fields

If you have a phone column in your CSV and it's empty and if the record in vtgier already has a phone, it gets deleted. What you would expect from a merge function is that it would keep the non-empty field instead of keeping the empty one.

For more context, see: http://vtiger-crm.2324883.n4.nabble.com/Vtigercrm-developers-How-to-import-and-overwrite-data-without-changing-record-IDs-td23209.html