Merge remote-tracking branch 'upstream/master' into rolling-sliding-w…

…indow

* upstream/master:
  add polyval to polyfit see also (pydata#5020)
  mention map_blocks in the docstring of apply_ufunc (pydata#5011)
  Switch backend API to v2 (pydata#4989)
  WIP: add new backend api documentation (pydata#4810)
  pin netCDF4=1.5.3 in min-all-deps (pydata#4982)
  fix matplotlib errors for single level discrete colormaps (pydata#4256)
  Adapt exception handling in CFTimeIndex.__sub__ and __rsub__ (pydata#5006)
  Update options.py (pydata#5000)
  Adjust tests to use updated pandas syntax for offsets (pydata#4537)
  add a combine_attrs parameter to Dataset.merge (pydata#4895)
  Support for dask.graph_manipulation (pydata#4965)
  raise on passing axis to Dataset.reduce methods (pydata#4940)

.github/workflows/ci-additional.yaml

@@ -42,7 +42,6 @@ jobs:
             "py37-min-all-deps",
             "py37-min-nep18",
             "py38-all-but-dask",
-            "py38-backend-api-v2",
             "py38-flaky",
           ]
     steps:
@@ -56,12 +55,7 @@ jobs:
 
       - name: Set environment variables
         run: |
-          if [[ ${{ matrix.env }} == "py38-backend-api-v2" ]] ;
-          then
-            echo "CONDA_ENV_FILE=ci/requirements/environment.yml" >> $GITHUB_ENV
-            echo "XARRAY_BACKEND_API=v2" >> $GITHUB_ENV
-
-          elif [[ ${{ matrix.env }} == "py38-flaky" ]] ;
+          if [[ ${{ matrix.env }} == "py38-flaky" ]] ;
           then
             echo "CONDA_ENV_FILE=ci/requirements/environment.yml" >> $GITHUB_ENV
             echo "PYTEST_EXTRA_FLAGS=--run-flaky --run-network-tests" >> $GITHUB_ENV

ci/requirements/py37-min-all-deps.yml

@@ -25,7 +25,9 @@ dependencies:
   - lxml=4.5  # Optional dep of pydap
   - matplotlib-base=3.1
   - nc-time-axis=1.2
-  - netcdf4=1.5
+# netcdf follows a 1.major.minor[.patch] convention (see https://github.com/Unidata/netcdf4-python/issues/1090)
+# bumping the netCDF4 version is currently blocked by #4491
+  - netcdf4=1.5.3
   - numba=0.48
   - numpy=1.17
   - pandas=1.0

doc/api-hidden.rst

@@ -811,3 +811,28 @@
    backends.DummyFileManager.acquire
    backends.DummyFileManager.acquire_context
    backends.DummyFileManager.close
+
+   backends.common.BackendArray
+   backends.common.BackendEntrypoint
+   backends.common.BackendEntrypoint.guess_can_open
+   backends.common.BackendEntrypoint.open_dataset
+
+   core.indexing.IndexingSupport
+   core.indexing.explicit_indexing_adapter
+   core.indexing.BasicIndexer
+   core.indexing.OuterIndexer
+   core.indexing.VectorizedIndexer
+   core.indexing.LazilyIndexedArray
+   core.indexing.LazilyVectorizedIndexedArray
+
+   conventions.decode_cf_variables
+
+   coding.variables.UnsignedIntegerCoder
+   coding.variables.CFMaskCoder
+   coding.variables.CFScaleOffsetCoder
+
+   coding.strings.CharacterArrayCoder
+   coding.strings.EncodedStringCoder
+
+   coding.times.CFTimedeltaCoder
+   coding.times.CFDatetimeCoder