function plugin( dir, cwd, subpath ) {
	var opts;
	var args;
	var proc;

	opts = {};
	opts.cwd = dir;
	opts.stdio = 'inherit';

	args = [];

	// Environment variables:
	if ( subpath ) {
		args.push( 'LIST_DIR_CONTRIBUTORS='+subpath );
	}
	// Target:
	args.push( 'stats-list-dir-contributors' );

	proc = spawn( 'make', args, opts );
	proc.on( 'error', onError );
	proc.on( 'close', onFinish );
}
Plugin to list contributors.

@param {string} dir - Makefile directory
@param {string} cwd - current working directory
@param {string} subpath - subdirectory path