BUG: RangeIndex.where throws AssertionError

[galipremsagar]

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• I have confirmed this bug exists on the latest version of pandas.

• (optional) I have confirmed this bug exists on the master branch of pandas.

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Note: Please read this guide detailing how to provide the necessary information for us to reproduce your bug.

Code Sample, a copy-pastable example

>>> import pandas as pd
>>> pd.__version__
'1.3.2'
>>> s = pd.RangeIndex(0, 5)
>>> s
RangeIndex(start=0, stop=5, step=1)
>>> import numpy as np
>>> v = np.array([False, False, True, True, True])
>>> s.where(v, 10)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/pgali/anaconda3/envs/cudf_dev/lib/python3.8/site-packages/pandas/core/indexes/base.py", line 4472, in where
    return self.putmask(~cond, other)
  File "/home/pgali/anaconda3/envs/cudf_dev/lib/python3.8/site-packages/pandas/core/indexes/base.py", line 4727, in putmask
    return type(self)._simple_new(values, name=self.name)
  File "/home/pgali/anaconda3/envs/cudf_dev/lib/python3.8/site-packages/pandas/core/indexes/range.py", line 164, in _simple_new
    assert isinstance(values, range)
AssertionError

Problem description

pandas RangeIndex is not allowing a where operation to be performed which was working in older versions of pandas i.e., 1.2.5

Expected Output

>>> import pandas as pd
>>> pd.__version__
'1.2.5'
>>> s = pd.RangeIndex(0, 5)
>>> s
RangeIndex(start=0, stop=5, step=1)
>>> import numpy as np
>>> v = np.array([False, False, True, True, True])
>>> s.where(v, 10)
Int64Index([10, 10, 2, 3, 4], dtype='int64')

Output of pd.show_versions()

INSTALLED VERSIONS

commit : 5f648bf
python : 3.8.10.final.0
python-bits : 64
OS : Linux
OS-release : 5.11.0-27-generic
Version : #29~20.04.1-Ubuntu SMP Wed Aug 11 15:58:17 UTC 2021
machine : x86_64
processor : x86_64
byteorder : little
LC_ALL : None
LANG : en_US.UTF-8
LOCALE : en_US.UTF-8

pandas : 1.3.2
numpy : 1.21.2
pytz : 2021.1
dateutil : 2.8.2
pip : 21.2.4
setuptools : 57.4.0
Cython : 0.29.24
pytest : 6.2.4
hypothesis : 6.15.0
sphinx : 4.1.2
blosc : None
feather : None
xlsxwriter : None
lxml.etree : None
html5lib : None
pymysql : None
psycopg2 : None
jinja2 : 3.0.1
IPython : 7.26.0
pandas_datareader: None
bs4 : 4.9.3
bottleneck : None
fsspec : 2021.07.0
fastparquet : None
gcsfs : None
matplotlib : None
numexpr : None
odfpy : None
openpyxl : None
pandas_gbq : None
pyarrow : 5.0.0
pyxlsb : None
s3fs : None
scipy : None
sqlalchemy : None
tables : None
tabulate : None
xarray : None
xlrd : None
xlwt : None
numba : 0.53.1

[simonjayhawkins]

Thanks @galipremsagar for the report

first bad commit: [6b8cc98] BUG: make Index.where behavior mirror Index.putmask behavior (#39412)

cc @jbrockmendel