Trying to detach line item before saving fails silently

[Tiffany Little]

Testing on a 3.13 server during the July AIG meeting.

If an invoice is already created but has not been saved yet, if you try to detach a line item it fails silently. The dotted line appears around the line item, but when the Save button is clicked the Webby screen appears briefly, the invoice refreshes and the line item remains.

We are opening this bug to preserve our findings, but weren't able to confirm on a separate test server. So this bug needs further confirmation.