Bug 30003: Prevent double up of point-of-sale items
This patch prevents the double submission of point-of-sale items when form validation fails at the first submission
Test plan
1. Navigate to /cgi-bin/koha/pos/pay.pl
2. Add an item from 'items to purchase'
3. Under 'collect payment', click submit without altering the form
4. See 'This field is required.'
5. Now, fill a value in 'Amount tendered' that satisfies or exceeds 'Amount being paid'
6. The payment should succeed
7. Navigate to /cgi-bin/koha/pos/register.pl
8. See duplicate lines in Transactions
9. Apply patch
10. Repeat 2-6
11. Navigate to /cgi-bin/koha/pos/register.pl
12. Confirm only a single line was added
Signed-off-by: Sally <sally.healey@cheshiresharedservices.gov.uk> Signed-off-by: Nick Clemens <nick@bywatersolutions.com> Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>