Comment 6 for bug 1635354

Remaining code and release notes force-pushed to same branch.

From the release notes:

Acquisitions invoices have 2 new fields:

* Close Date -- This is set to the time when the ACQ user clicks the "Close" button in the invoice interface.
  ** This field 'replaces' the existing 'complete' field. An invoice is considered complete if a close date value is set.
* Closed By -- This is set to the logged in staff user who performs the "Close" action.

As with the now-defunct 'complete' field, these new fields are cleared in the event an invoice is reopened.

These new fields are visible in the invoice interface under the 'Show Details' action for closed invoices.

Upgrading Invoice Reports
+++++++++++++++++++++++++

Existing report templates that reference the invoice 'complete' field should be modified to check whether the new close_date field is NOT NULL instead.

Other Upgrade Considerations
++++++++++++++++++++++++++++

At deploy time, all invoices with a 'complete' value of TRUE will have their 'close_date' field set to NOW. A value is required, since this field is now the source of whether an invoice is open or closed.

However, no values will be applied to the closed_by field for already closed invoices.

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To test:
[1] Create an ACQ invoice.
[2] Close the invoice
[3] Confirm the "Show Details" action now displays the new Close Date and Closed By fields in the invoice summary along the top.
[4] Reopen the invoice and confirm the fields no longer display and that the values have been cleared in the DB.

Adding pullreq.