tests/test-dirstate-nonnormalset.t

run-tests: fix whitelist/blacklist with directories on Windows

The file name is resolved with `os.path.relpath()` in the `Test` constructor,
which yields `\` on Windows.  That doesn't match the `/` separator when using
MSYS tools to build the list, and it isn't obvious that this is the problem
because directory separators can mostly be used interchangeably.  The
`--test-list` argument already seems to be properly handled.

  $ cat >> $HGRCPATH << EOF
  > [command-templates]
  > log="{rev}:{node|short} ({phase}) [{tags} {bookmarks}] {desc|firstline}\n"
  > [extensions]
  > dirstateparanoidcheck = $TESTDIR/../contrib/dirstatenonnormalcheck.py
  > [experimental]
  > nonnormalparanoidcheck = True
  > [devel]
  > all-warnings=True
  > EOF
  $ mkcommit() {
  >    echo "$1" > "$1"
  >    hg add "$1"
  >    hg ci -m "add $1"
  > }

  $ hg init testrepo
  $ cd testrepo
  $ mkcommit a
  $ mkcommit b
  $ mkcommit c
  $ hg status