Accounting Code column is not populated in Contribution Exports

Find contributions > Export > Primary Fields

There is a column for Accounting Code (column header is currently 'accounting_code' - s/b 'Accounting Code'). However data is missing in the column.

Folks who are currently using 4.2 and earlier will expect this column to be populated with accounting code from the "Income Account is" financial account for that contribution's financial type.