Bug 9078 - fixing exceptions broke tests

Bug 9078 - fixing exceptions broke tests

Fixing the holiday exceptions arised a problem with how the test data was constructed.
This made several tests fail.

This patch fixes the add_holiday function. Tests should pass now.

Sponsored-by: Universidad Nacional de Córdoba
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Passed-QA-by: Paul Poulain <paul.poulain@biblibre.com>
Signed-off-by: Jared Camins-Esakov <jcamins@cpbibliography.com>