lib/mkdirs/win32.js
function getRootPath (p) {
  p = path.normalize(path.resolve(p)).split(path.sep)
  if (p.length > 0) return p[0]
  return null
}
function getRootPath (p) {
  p = path.normalize(path.resolve(p)).split(path.sep)
  if (p.length > 0) return p[0]
  return null
}
function getRootPath ( p ) { p = path . normalize ( path . resolve ( p ) ) . split ( path . sep ) if ( p . length > 0 ) return p [ 0 ] return null }
get drive on windows
get drive on windows