∀ {C : Type u} [inst : CategoryTheory.Category.{v, u} C] [inst_1 : CategoryTheory.Limits.HasZeroObject C]
  [inst_2 : CategoryTheory.HasShift C ℤ] [inst_3 : CategoryTheory.Preadditive C]
  [inst_4 : ∀ (n : ℤ), (CategoryTheory.shiftFunctor C n).Additive] [hC : CategoryTheory.Pretriangulated C]
  {T T' : CategoryTheory.Pretriangulated.Triangle C} (e : T ≅ T')
  (hT : T ∈ CategoryTheory.Pretriangulated.distinguishedTriangles),
  (CategoryTheory.Pretriangulated.shortComplexOfDistTriangleIsoOfIso e hT).inv.τ₁ = e.inv.hom₁