Goal:
  
  A : Type
  P : list A → A → Type
  l : list A
  a : All_fold P l
  b : All_fold P l
  H : NoConfusionHom_All_fold A P l a b
  ============================
   (a = b)


DEBUG:Going to execute:
match goal with
           | |- ?f ?a ?b _ = _ => solve_noconf_hom_inv_eq a b
           | |- ?R ?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 ])
           end