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


DEBUG:Going to execute:
intros; CoreTactics.on_last_hyp ltac:(fun id => destruct id);
            CoreTactics.on_last_hyp
             ltac:(fun id =>
                     CoreTactics.destruct_sigma id; DepElim.depelim id);
            simpl