Bug 28482: [19.11.x] Refresh line from DB to get stored value

Before checking if the amount is 0 we get the stored value from the DB. This
ensures any amounts beyond the 6 digit precision we store will be removed.

To test:
1 - Add a processing fee of 15 to an itemtype
2 - Add an item of that type, set the replacement fee to 12.63
3 - Set MarkLostItemsAsReturned to 'On payment' only
4 - Set  WhenLostChargeReplacementFee to 'Charge'
5 - Checkout the item to a patron
6 - Mark the item lost
7 - Reload patron and confirm they are charged 27.63
8 - Go to accounting, pay amount, pay 27.63
9 - Item is still lost and not returned
10 - Apply patch
11 - Checkin the item
12 - Checkout to another patron
13 - Mark lost
14 - Patron charged 27.63
15 - Pay amount, 27.63
16 - Item returned!

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>

Signed-off-by: Wainui Witika-Park <wainuiwitikapark@catalyst.net.nz>

Koha/Account/Line.pm

@@ -263,6 +263,8 @@ sub apply {
             $self->amountoutstanding( $available_credit * -1 )->store;
             $debit->amountoutstanding( $owed - $amount_to_cancel )->store;
 
+            $debit->discard_changes; # Refresh values from DB to clear floating point remainders
+
             # Same logic exists in Koha::Account::pay
             if (   $debit->amountoutstanding == 0
                 && $debit->itemnumber