Bug 19208 - Pay select option doesn't pay the selected fine

Bug 19208 - Pay select option doesn't pay the selected fine

The "Pay selected" option on the Fines tab in the borrower account page doesn't work as intended.
The fine on top of the list gets the amount deducted, even if another fine is choosen from the list.

Test Plan:
1) Create two or three fines, using the Create manual invoice function.
2) Choose one of the fines (not the one on the top) and click Pay selected
3) Pay a partial amount
4) Go back to the Pay fines tab an notice that the fine you selected has not changed. Instead, either the top fine or the total (see attachment) has ben affected.
5) Apply this patch
6) Repeat steps 1-3
7) Note the correct fine is paid

Signed-off-by: Andreas Hedström Mace <andreas.hedstrom.mace@sub.su.se>
Signed-off-by: Julian Maurice <julian.maurice@biblibre.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>