t / t4135 / git-plain.diffon commit tree-diff: convert diff_root_tree_sha1() to just call diff_tree_sha1 with old=NULL (0b707c3)
   1diff --git a/postimage.txt b/postimage.txt
   2new file mode 100644
   3index 0000000..eff0c54
   4--- /dev/null
   5+++ b/postimage.txt
   6@@ -0,0 +1 @@
   7+postimage