Goal:
  
  A : Type
  P : list A → A → Type
  l : list A
  a : All_fold P l
  b : All_fold P l
  e : NoConfusionHom_All_fold A P l a b
  ============================
   (noConfusionHom_All_fold_obligation_2 A P l a b
      (noConfusionHom_All_fold_obligation_1 A P l a b e) = e)


DEBUG:Going to execute:
fun a b =>
             CoreTactics.destruct_sigma a; CoreTactics.destruct_sigma b;
              destruct a; DepElim.depelim b; simpl in * |-;
              CoreTactics.on_last_hyp
               ltac:(fun id =>
                       hnf in id;
                        CoreTactics.destruct_tele_eq id || DepElim.depelim id);
              (solve [ constructor || DepElim.simpl_equations; constructor ])