Following the advice given in review [1], we could put the
conditional inside the scripts-library to simplify the behavior
inside the gate-check-commit script.
On top of that, if we pipe to || true, the function wouldn't
fail on branches where the function/vars are not defined,
cleaning the code further.
[1]: https://review.openstack.org/#/c/531131/2
Change-Id: Icda339747267cf6bf514d45878c26533b5341f83