Re: exact semantics of union mounts (and TRYEMULROOT)

[Robert Elz <kre%munnari.OZ.AU@localhost>]

    Date:        Mon, 10 Jul 2017 16:35:45 -0400 (EDT)
    From:        Mouse <mouse%Rodents-Montreal.ORG@localhost>
    Message-ID:  <201707102035.QAA06237%Stone.Rodents-Montreal.ORG@localhost>

  | >> So I think we need to test all layers before creating anything.
  | > Of course.
  | 
  | Well...if there's a whiteout (at any layer), you need not look at
  | layers below it, I think.

Yes.   Similarly if the file is found, there is no need to look at
further lower layers ... just go down the list (in most cases there
will be just 2) until an answer is discovered (does, or does not, exist)
or until there is nowhere left to look (so does not exist).

kre