tests/test-empty-dir.t

merge: skip syntactic path checks in [_checkunknownfile]

We don't need to check the paths syntactically, since they are coming from
diffing the revisions, so hopefully already checked on the way in.

We still need to check what's on the filesystem, to avoid traversing the
symlinks or subdirs, which we can't know about statically.

Also, we use the directory audit to elide [isfileorlink],
this removing ~all lstat calls from hg updates from-empty.

  $ hg init

  $ echo 123 > a
  $ hg add a
  $ hg commit -m "first" a

  $ mkdir sub
  $ echo 321 > sub/b
  $ hg add sub/b
  $ hg commit -m "second" sub/b

  $ cat sub/b
  321

  $ hg co 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved

  $ cat sub/b 2>/dev/null || echo "sub/b not present"
  sub/b not present

  $ test -d sub || echo "sub not present"
  sub not present