$ git diff-tree --root -r --abbrev=4 initial
444ac553ac7612cc88969031b02b3767fb8a353a
:000000 100644 0000... 35d2... A	dir/sub
:000000 100644 0000... 01e7... A	file0
:000000 100644 0000... 01e7... A	file2
$