112. Every insurance contract in which the automobiles insured are not designated expressly, affording protection against the pecuniary consequences of the civil liability of garagists, must cover by priority over any other insurance contract, any property damage caused by automobiles not belonging to the garagist which are at the time of the accident the object of a garagist’s professional activity; the protection of the other insurance contracts applies only in the case of insufficiency of the protection of the garagist’s insurance contract.