Xr unitsfix

[pp-mo]

Discovered that the problem with current proposed v1.1 is ..

• specific to xarray 2024.2.0
• results of direct and via-ncdata load are identical according to xr.Dataset.identical()
• on save via xr.Dataset.to_netcdf() however, the units does/does-not strip a midnight time-of-day when the data array is lazy/real (i.e. sometimes get "hours since 1970-01-01" instead of the "hours since 1970-01-01 00:00:00" in the encoding)
  • quirky: possibly only happens with scalar data, and seems to also depend on 'unconnected' dims / extra variables
• the Dataset.encodings are also non-identical, but Dataset.identical() does not insist on this
  • variable encodings also lack a bunch of compression options
  • main (Dataset) encoding notably lacks an "unlimited_dims" entry : this is a known limitation, and should maybe be fixed