It is clear that long hair can be a hazard to a defender in a 'streetfight' scenario where combat breaks out and you need to defend yourself suddenly and unexpectedly. Hair can get in your eyes and, much more severe, it can be pulled and used as a weapon against you. In sparring that simulates streetfighting it is clear that having hair long enough to grab can be a significant vulnerability.
What can one do to minimize harm from having long hair? ...aside from cutting it during times of peace, that is. Protecting it, as you would protect your face and head in general, is one obvious answer. Is there anything else that can be done, in advance or during combat, to keep it from being used against you?
Note that this is not a duplicate of What are good solutions for MMA training with half long hair? because that question focused on MMA training and matches whereas this question focuses on general self-defense in unideal, unplanned conditions.