issues: 546303413

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id node_id number title user state locked assignee milestone comments created_at updated_at closed_at author_association active_lock_reason draft pull_request body reactions performed_via_github_app state_reason repo type
546303413 MDU6SXNzdWU1NDYzMDM0MTM= 3666 Raise nice error when attempting to concatenate CFTimeIndex & DatetimeIndex 22454970 open 0     9 2020-01-07T14:08:03Z 2021-07-08T17:43:58Z   NONE      

MCVE Code Sample

```python import subprocess import sys import wget import glob

def install(package): subprocess.check_call([sys.executable, "-m", "pip", "install", package]) try: from xclim import ensembles except: install('xclim') from xclim import ensembles

outdir = 'tmp' url = [] url.append('https://github.com/Ouranosinc/xclim/raw/master/tests/testdata/EnsembleStats/BCCAQv2+ANUSPLIN300_ACCESS1-0_historical+rcp45_r1i1p1_1950-2100_tg_mean_YS.nc') url.append('https://github.com/Ouranosinc/xclim/raw/master/tests/testdata/EnsembleStats/BCCAQv2+ANUSPLIN300_BNU-ESM_historical+rcp45_r1i1p1_1950-2100_tg_mean_YS.nc') url.append('https://github.com/Ouranosinc/xclim/raw/master/tests/testdata/EnsembleStats/BCCAQv2+ANUSPLIN300_CCSM4_historical+rcp45_r1i1p1_1950-2100_tg_mean_YS.nc') url.append('https://github.com/Ouranosinc/xclim/raw/master/tests/testdata/EnsembleStats/BCCAQv2+ANUSPLIN300_CCSM4_historical+rcp45_r2i1p1_1950-2100_tg_mean_YS.nc') for u in url: wget.download(u,out=outdir) datasets = glob.glob(f'{outdir}/1950.nc') ens1 = ensembles.create_ensemble(datasets) print(ens1)

```

Expected Output

Following advice of @dcherian (https://github.com/Ouranosinc/xclim/issues/281#issue-508073942) we have started testing builds of xclim against the master branch as well as the current release:

Using xarray 0.14.1 via pip the above code generates a concatenated dataset with new added dimension 'realization'

Problem Description

using xarray@master the xclim.ensembles.create_ensemble call gives the following error:

Traceback (most recent call last): File "/home/travis/.PyCharmCE2019.3/config/scratches/scratch_26.py", line 23, in <module> ens1 = ensembles.create_ensemble(datasets) File "/home/travis/github_xclim/xclim/xclim/ensembles.py", line 83, in create_ensemble data = xr.concat(list1, dim=dim) File "/home/travis/.conda/envs/xclim_dev/lib/python3.7/site-packages/xarray/core/concat.py", line 135, in concat return f(objs, dim, data_vars, coords, compat, positions, fill_value, join) File "/home/travis/.conda/envs/xclim_dev/lib/python3.7/site-packages/xarray/core/concat.py", line 439, in _dataarray_concat join=join, File "/home/travis/.conda/envs/xclim_dev/lib/python3.7/site-packages/xarray/core/concat.py", line 303, in _dataset_concat *datasets, join=join, copy=False, exclude=[dim], fill_value=fill_value File "/home/travis/.conda/envs/xclim_dev/lib/python3.7/site-packages/xarray/core/alignment.py", line 298, in align index = joiner(matching_indexes) File "/home/travis/.conda/envs/xclim_dev/lib/python3.7/site-packages/pandas/core/indexes/base.py", line 2385, in __or__ return self.union(other) File "/home/travis/.conda/envs/xclim_dev/lib/python3.7/site-packages/pandas/core/indexes/base.py", line 2517, in union return self._union_incompatible_dtypes(other, sort=sort) File "/home/travis/.conda/envs/xclim_dev/lib/python3.7/site-packages/pandas/core/indexes/base.py", line 2436, in _union_incompatible_dtypes return Index.union(this, other, sort=sort).astype(object, copy=False) File "/home/travis/.conda/envs/xclim_dev/lib/python3.7/site-packages/pandas/core/indexes/base.py", line 2517, in union return self._union_incompatible_dtypes(other, sort=sort) .... File "/home/travis/.conda/envs/xclim_dev/lib/python3.7/site-packages/pandas/core/indexes/base.py", line 498, in __new__ return DatetimeIndex(subarr, copy=copy, name=name, **kwargs) File "/home/travis/.conda/envs/xclim_dev/lib/python3.7/site-packages/pandas/core/indexes/datetimes.py", line 334, in __new__ int_as_wall_time=True, File "/home/travis/.conda/envs/xclim_dev/lib/python3.7/site-packages/pandas/core/arrays/datetimes.py", line 446, in _from_sequence int_as_wall_time=int_as_wall_time, File "/home/travis/.conda/envs/xclim_dev/lib/python3.7/site-packages/pandas/core/arrays/datetimes.py", line 1854, in sequence_to_dt64ns data, copy = maybe_convert_dtype(data, copy) File "/home/travis/.conda/envs/xclim_dev/lib/python3.7/site-packages/pandas/core/arrays/datetimes.py", line 2060, in maybe_convert_dtype elif is_extension_type(data) and not is_datetime64tz_dtype(data): File "/home/travis/.conda/envs/xclim_dev/lib/python3.7/site-packages/pandas/core/dtypes/common.py", line 1734, in is_extension_type if is_categorical(arr): File "/home/travis/.conda/envs/xclim_dev/lib/python3.7/site-packages/pandas/core/dtypes/common.py", line 387, in is_categorical return isinstance(arr, ABCCategorical) or is_categorical_dtype(arr) File "/home/travis/.conda/envs/xclim_dev/lib/python3.7/site-packages/pandas/core/dtypes/common.py", line 708, in is_categorical_dtype return CategoricalDtype.is_dtype(arr_or_dtype) File "/home/travis/.conda/envs/xclim_dev/lib/python3.7/site-packages/pandas/core/dtypes/base.py", line 256, in is_dtype if isinstance(dtype, (ABCSeries, ABCIndexClass, ABCDataFrame, np.dtype)): File "/home/travis/.conda/envs/xclim_dev/lib/python3.7/site-packages/pandas/core/dtypes/generic.py", line 9, in _check return getattr(inst, attr, "_typ") in comp RecursionError: maximum recursion depth exceeded while calling a Python object

Output of xr.show_versions()

INSTALLED VERSIONS ------------------ commit: None python: 3.7.5 (default, Oct 25 2019, 15:51:11) [GCC 7.3.0] python-bits: 64 OS: Linux OS-release: 4.15.0-74-generic machine: x86_64 processor: x86_64 byteorder: little LC_ALL: None LANG: en_CA.UTF-8 LOCALE: en_CA.UTF-8 libhdf5: 1.10.4 libnetcdf: 4.6.3 xarray: 0.14.1+37.gdb36c5c0 pandas: 0.25.3 numpy: 1.17.4 scipy: 1.3.1 netCDF4: 1.5.3 pydap: None h5netcdf: 0.7.4 h5py: 2.9.0 Nio: None zarr: None cftime: 1.0.4.2 nc_time_axis: None PseudoNetCDF: None rasterio: 1.1.1 cfgrib: None iris: None bottleneck: 1.3.1 dask: 2.6.0 distributed: 2.6.0 matplotlib: 3.1.1 cartopy: None seaborn: None numbagg: None setuptools: 41.6.0.post20191030 pip: 19.3.1 conda: None pytest: 5.2.2 IPython: None sphinx: None 
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     13221727 issue

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