This reverts commit 61b7334.

…equiv

* 'master' of github.com:pydata/xarray: (28 commits)
  Add nanmedian for dask arrays (pydata#3604)
  added pyinterp to related projects (pydata#3655)
  Allow incomplete hypercubes in combine_by_coords (pydata#3649)
  concat keeps attrs from first variable. (pydata#3637)
  Extend DatetimeAccessor properties and support `.dt` accessor for Timedelta (pydata#3612)
  update readthedocs.yml (pydata#3639)
  silence sphinx warnings round 3 (pydata#3602)
  Fix/quantile wrong errmsg (pydata#3635)
  Provide shape info in shape mismatch error. (pydata#3619)
  Minor doc fixes (pydata#3615)
  Respect user-specified coordinates attribute. (pydata#3487)
  Add Facetgrid.row_labels & Facetgrid.col_labels (pydata#3597)
  Fix pint integration tests (pydata#3600)
  Minor fix to combine_by_coords to allow for the combination of CFTimeIndexes separated by large time intervals (pydata#3543)
  Fix map_blocks HLG layering (pydata#3598)
  Silence sphinx warnings: Round 2 (pydata#3592)
  2x~5x speed up for isel() in most cases (pydata#3533)
  remove xarray again (pydata#3591)
  fix plotting with transposed nondim coords. (pydata#3441)
  make coarsen reductions consistent with reductions on other classes (pydata#3500)
  ...

Co-Authored-By: crusaderky <[email protected]>

* upstream/master: (23 commits)
  Feature/align in dot (pydata#3699)
  ENH: enable `H5NetCDFStore` to work with already open h5netcdf.File a… (pydata#3618)
  One-off isort run (pydata#3705)
  hardcoded xarray.__all__ (pydata#3703)
  Bump mypy to v0.761 (pydata#3704)
  remove DataArray and Dataset constructor deprecations for 0.15  (pydata#3560)
  Tests for variables with units (pydata#3654)
  Add an example notebook using apply_ufunc to vectorize 1D functions (pydata#3629)
  Use encoding['dtype'] over data.dtype when possible within CFMaskCoder.encode (pydata#3652)
  allow passing any iterable to drop when dropping variables (pydata#3693)
  Typo on DataSet/DataArray.to_dict documentation (pydata#3692)
  Fix mypy type checking tests failure in ds.merge (pydata#3690)
  Explicitly convert result of pd.to_datetime to a timezone-naive type (pydata#3688)
  ds.merge(da) bugfix (pydata#3677)
  fix docstring for combine_first: returns a Dataset (pydata#3683)
  Add option to choose mfdataset attributes source. (pydata#3498)
  How do I add a new variable to dataset. (pydata#3679)
  Add map_blocks example to whats-new (pydata#3682)
  Make dask names change when chunking Variables by different amounts. (pydata#3584)
  raise an error when renaming dimensions to existing names (pydata#3645)
  ...

… optimize-lazy-equiv

* 'optimize-lazy-equiv' of github.com:dcherian/xarray:
  Update xarray/core/variable.py