[FIX] int(base_calendar_id) can return an exception instead of false
[FIX] int(base_calendar_id) can return an exception instead of false

camptocamp/ngo-addons-backport,gdgellatly/OCB1,grap/OCB,grap/OCB,vrenaville/ngo-addons-backport,gdgellatly/OCB1,vrenaville/ngo-addons-backport,vrenaville/ngo-addons-backport,credativUK/OCB,camptocamp/ngo-addons-backport,grap/OCB,credativUK/OCB,gdgellatly/OCB1,grap/OCB,camptocamp/ngo-addons-backport,grap/OCB,OpenPymeMx/OCB,gdgellatly/OCB1,credativUK/OCB,gdgellatly/OCB1,credativUK/OCB,camptocamp/ngo-addons-backport,gdgellatly/OCB1,credativUK/OCB,OpenPymeMx/OCB,vrenaville/ngo-addons-backport,credativUK/OCB,OpenPymeMx/OCB,grap/OCB,gdgellatly/OCB1,camptocamp/ngo-addons-backport,credativUK/OCB,vrenaville/ngo-addons-backport,OpenPymeMx/OCB,OpenPymeMx/OCB,OpenPymeMx/OCB,grap/OCB,camptocamp/ngo-addons-backport,vrenaville/ngo-addons-backport,credativUK/OCB,OpenPymeMx/OCB,camptocamp/ngo-addons-backport,vrenaville/ngo-addons-backport,vrenaville/ngo-addons-backport,camptocamp/ngo-addons-backport,grap/OCB,OpenPymeMx/OCB,gdgellatly/OCB1