Bug 27580: Regression tests

Bug 27580: Regression tests

This test makes all the generated sample items have undef copynumber,
and all rules are added copynumber => [ 2 ] on the tests as
suggested by Andrew on his failing example.

The tests are expected to pass. i.e. copynumber is clearly not equal to
2, so those items shouldn't be hidden.

To test:
1. Apply this patch
2. Run:
   $ kshell
  k$ prove t/db_dependent/Koha/Items.t
=> FAIL: Tests fail! undef is considered in [ 2 ]

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Andrew Fuerste-Henry <andrew@bywatersolutions.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>