I think this was added in https://git.kernel.org/cgit/git/git.git/commit/?id=ec55559f937727bcb0fa8a3dfe6af68c188e968a which was first released as 1.8.2 (and I think not documented until 1.8.4 but whatever). T5554#133984 has some discussion on supported versions, which included more reasonable recent 1.7.x versions.