issues: 271036342

I think this is a regression in the current 0.10.0rc1:

Code Sample

```python import xarray as xr ds = xr.open_dataset('cesm_data.nc', decode_cf=False) ds.temp.isel(time=ds.time < 274383) # throws an error

---

NotImplementedError Traceback (most recent call last) <ipython-input-18-a5c4179cd02d> in <module>() ----> 1 ds.temp.isel(time=ds.time < 274383)

~/.pyvirtualenvs/py3/lib/python3.5/site-packages/xarray/core/dataarray.py in isel(self, drop, indexers) 717 DataArray.sel 718 """ --> 719 ds = self._to_temp_dataset().isel(drop=drop, indexers) 720 return self._from_temp_dataset(ds) 721

~/.pyvirtualenvs/py3/lib/python3.5/site-packages/xarray/core/dataset.py in isel(self, drop, indexers) 1278 for name, var in iteritems(self._variables): 1279 var_indexers = {k: v for k, v in indexers_list if k in var.dims} -> 1280 new_var = var.isel(var_indexers) 1281 if not (drop and name in var_indexers): 1282 variables[name] = new_var

~/.pyvirtualenvs/py3/lib/python3.5/site-packages/xarray/core/variable.py in isel(self, **indexers) 771 if dim in indexers: 772 key[i] = indexers[dim] --> 773 return self[tuple(key)] 774 775 def squeeze(self, dim=None):

~/.pyvirtualenvs/py3/lib/python3.5/site-packages/xarray/core/variable.py in getitem(self, key) 595 """ 596 dims, index_tuple, new_order = self._broadcast_indexes(key) --> 597 data = self._indexable_data[index_tuple] 598 if new_order: 599 data = np.moveaxis(data, range(len(new_order)), new_order)

~/.pyvirtualenvs/py3/lib/python3.5/site-packages/xarray/core/indexing.py in getitem(self, key) 414 415 def getitem(self, key): --> 416 return type(self)(_wrap_numpy_scalars(self.array[key])) 417 418 def setitem(self, key, value):

~/.pyvirtualenvs/py3/lib/python3.5/site-packages/xarray/core/indexing.py in getitem(self, key) 394 395 def getitem(self, key): --> 396 return type(self)(_wrap_numpy_scalars(self.array[key])) 397 398 def setitem(self, key, value):

~/.pyvirtualenvs/py3/lib/python3.5/site-packages/xarray/core/indexing.py in getitem(self, key) 361 362 def getitem(self, key): --> 363 return type(self)(self.array, self._updated_key(key)) 364 365 def setitem(self, key, value):

~/.pyvirtualenvs/py3/lib/python3.5/site-packages/xarray/core/indexing.py in _updated_key(self, new_key) 336 raise NotImplementedError( 337 'Vectorized indexing for {} is not implemented. Load your ' --> 338 'data first with .load() or .compute().'.format(type(self))) 339 new_key = iter(expanded_indexer(new_key, self.ndim)) 340 key = []

NotImplementedError: Vectorized indexing for <class 'xarray.core.indexing.LazilyIndexedArray'> is not implemented. Load your data first with .load() or .compute().

``` Here is the file: cesm_data.nc.zip

Expected Output

This used to work in v0.9

Output of xr.show_versions()

INSTALLED VERSIONS ------------------ commit: None python: 3.5.2.final.0 python-bits: 64 OS: Linux OS-release: 4.10.0-38-generic machine: x86_64 processor: x86_64 byteorder: little LC_ALL: None LANG: en_US.UTF-8 LOCALE: en_US.UTF-8 xarray: 0.10.0rc1 pandas: 0.21.0 numpy: 1.13.3 scipy: 1.0.0 netCDF4: 1.3.0 h5netcdf: None Nio: None bottleneck: 1.2.1 cyordereddict: None dask: 0.15.4 matplotlib: 2.1.0 cartopy: 0.15.1 seaborn: 0.8.1 setuptools: 36.6.0 pip: 9.0.1 conda: None pytest: 3.2.3 IPython: 6.2.1 sphinx: 1.6.5