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.

debugdirstate: simplify date handling after e7ed5d07cc4c used fixed format