b/c of umask, the default mode for ensureDir is 0777 & (~process.umask())

[qiulang]

Because of umask, calling ensureDir/ensureDirSync without fs.chmodSync, the actual mode is not the same as the intended mode. I think it is better to mention this in https://github.com/jprichardson/node-fs-extra/blob/master/docs/ensureDir.md especially for someone who is not familiar with umask.

Besides, I feel it is unnecessary to call this in mkdirs.js because node will take care of that.

  if (mode === undefined) {
    mode = o777 & (~process.umask())
  }

Refer to

1. Using fs.mkdir() make a directory according the Docs the argument 'mode' defaults to 0o777, but actually it's not. nodejs/node#15092
2. https://stackoverflow.com/questions/30815154/fs-mkdir-is-creating-the-directory-with-different-permissions-than-those-speci

[RyanZim]

PR welcome to clarify the docs. Thanks for the tip about explicitly doing it in the code, need to look into that.

[zensabbah]

A simple explanation of mode = 0o2775? Should it be chmod 775?

[RyanZim]

Explicit code usage fixed in #791. Still needs documented; will try to get that done.

[RyanZim]

Actually, was under the impression Node has a note about this; since they don't, not a priority to do it here.