Goal:
  
  A : Type
  P : list A → A → Type
  d : A
  Γ : list A
  a : All_fold P Γ
  p : P Γ d
  b : All_fold P Γ
  p0 : P Γ d
  H : NoConfusionHom_All_fold A P (d :: Γ) (All_fold_cons P a p)
        (All_fold_cons P b p0)
  ============================
   (let H := CoreTactics.block in All_fold_cons P a p = All_fold_cons P b p0)


DEBUG:Going to execute:
CoreTactics.intros_until_block