Bug 18246: Patron card creator: Unit not always displays properly in layouts

To reproduce:

1) Create a new layout
2) Select an unit in "Units selection"
3) Save
4) Edit layout again
5) Select other unit, e.g. 'SI Centimeter'
6) Save
7) Repeat
8) Edit again
Error: Latest unit seems to stick and can no longer be changed, because
in units drop down, multiple untis are marked as selected.

To test:
1) Apply patch
2) Repeat steps above, verify that value for units always display as expected.

Signed-off-by: Jesse Maseto <jesse@bywatersolutions.com>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>

Signed-off-by: Brendan A Gallagher <brendan@bywatersolutions.com>
(cherry picked from commit 37da40b323)
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>

patroncards/edit-layout.pl

@@ -146,6 +146,8 @@ if ($op eq 'edit') {
     foreach my $unit (@$units){
         if ($unit->{'type'} eq $layout->get_attr('units')) {
             $unit->{'selected'} = 1;
+        } else {
+            $unit->{'selected'} = 0;
         }
     }