This git subcommand is a super-simple tool for importing repositories for use with the subtree merge strategy described at https://www.kernel.org/pub/software/scm/git/docs/howto/using-merge-subtree.html.
Place this script in your $PATH and run
$ git import-subtree <destination> <remote> <ref>
to create a new directory named <destination> containing the contents of the
specified <remote> repository at the specified <ref>, preserving the
history of the remote repository.