tests/test-pull-permission.t

hardlink: check directory's st_dev when copying files

Previously, when copying a file, copyfiles will compare src's st_dev with
dirname(dst)'s st_dev, to decide whether to enable hardlink or not.

That could have issues on Linux's overlayfs, where stating directories could
result in different st_dev from st_dev of stating files, even if both the
directories and the files exist in the overlay's upperdir.

This patch fixes it by checking dirname(src) instead. It's more consistent
because we are checking directories for both src and dest.

That fixes test-hardlinks.t running on common Docker setups.

#require unix-permissions no-root

  $ hg init a
  $ cd a
  $ echo foo > b
  $ hg add b
  $ hg ci -m "b"

  $ chmod -w .hg/store

  $ cd ..

  $ hg clone a b
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ chmod +w a/.hg/store # let test clean up

  $ cd b
  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  1 files, 1 changesets, 1 total revisions

  $ cd ..