+# if you run 'git_commit_non_empty_tree "$@"' in a commit filter,
+# it will skip commits that leave the tree untouched, commit the other.
+git_commit_non_empty_tree()
+{
+ if test $# = 3 && test "$1" = $(git rev-parse "$3^{tree}"); then
+ map "$3"
+ else
+ git commit-tree "$@"
+ fi
+}