tests/test-diff-newlines.t

debugdirstate: don't hide date field with --nodate, just show 'set'/'unset'

The value of the dirstate date field cannot be used in tests and we thus have
to use debugdirstate with --nodate. It is however still very helpful to be able
to see whether the date field has been set or still is unset. The absence of
that information made it hard to debug some largefile dirstate issues.

This change _could_ make the test suite more unstable ... but that would be
places where the test suite or the code should be made more stable. (Note:
'unset' with the magic negative sizes is reliable. 'unset' for normal sizes
would probably not be reliable, but there is no such occurrences in the test
suite and it should thus be reliable.)

This output wastes more horizontal space in the --nodate output, but it also
makes things simpler that the output format always is the same. It is just a
debug command so let's keep it simple.

  $ hg init

  $ $PYTHON -c 'file("a", "wb").write("confuse str.splitlines\nembedded\rnewline\n")'
  $ hg ci -Ama -d '1 0'
  adding a

  $ echo clean diff >> a
  $ hg ci -mb -d '2 0'

  $ hg diff -r0 -r1
  diff -r 107ba6f817b5 -r 310ce7989cdc a
  --- a/a	Thu Jan 01 00:00:01 1970 +0000
  +++ b/a	Thu Jan 01 00:00:02 1970 +0000
  @@ -1,2 +1,3 @@
   confuse str.splitlines
   embedded\r (no-eol) (esc)
  newline
  +clean diff