No restraining order or injunctive relief shall be granted to any complainant who has failed to comply with any obligation imposed by law which is involved in the labor dispute in question, or who has failed to make very [every] reasonable effort to settle such dispute either by negotiation or with the aid of any available machinery of governmental mediation of voluntary arbitration, but nothing herein contained shall be deemed to require the court to await the action of such tribunal if irreparable injury is threatened.