Now, you will get the rewritten history saved in HEAD.
+As with using `rm filename`, `git rm --cached filename` will fail
+if the file is absent from the tree of a commit. If it is not important
+whether the file is already absent from the tree, you can use
+`git rm --cached --ignore-unmatch filename` instead.
To rewrite the repository to look as if `foodir/` had been its project
root, and discard all other history: