Pandas 1.03: pandas.tseries.offsets.QuarterBegin not showing correct date

[patrickxli]

Code Sample, a copy-pastable example if possible

from datetime import datetime
from pandas.tseries.offsets import QuarterBegin

now = datetime.datetime(2020, 1, 12)

now - QuarterBegin()

Problem description

The code shows the following results:

now - QuarterBegin()
Out[28]: Timestamp('2019-12-01 00:00:00')

which is not expected.

Expected Output

Timestamp('2020-01-01 00:00:00')

Output of pd.show_versions()

[paste the output of pd.show_versions() here below this line]
pd.show_versions()
INSTALLED VERSIONS

commit : None
python : 3.7.6.final.0
python-bits : 64
OS : Windows
OS-release : 10
machine : AMD64
processor : Intel64 Family 6 Model 142 Stepping 9, GenuineIntel
byteorder : little
LC_ALL : None
LANG : None
LOCALE : None.None
pandas : 1.0.3
numpy : 1.18.2
pytz : 2019.3
dateutil : 2.8.1
pip : 20.0.2
setuptools : 45.2.0.post20200210
Cython : 0.29.15
pytest : 5.3.5
hypothesis : 5.5.4
sphinx : 2.4.0
blosc : None
feather : None
xlsxwriter : 1.2.7
lxml.etree : 4.5.0
html5lib : 1.0.1
pymysql : None
psycopg2 : None
jinja2 : 2.11.1
IPython : 7.12.0
pandas_datareader: None
bs4 : 4.8.2
bottleneck : 1.3.2
fastparquet : None
gcsfs : None
lxml.etree : 4.5.0
matplotlib : 3.1.3
numexpr : 2.7.1
odfpy : None
openpyxl : 3.0.3
pandas_gbq : None
pyarrow : None
pytables : None
pytest : 5.3.5
pyxlsb : None
s3fs : None
scipy : 1.4.1
sqlalchemy : 1.3.13
tables : 3.6.1
tabulate : None
xarray : None
xlrd : 1.2.0
xlwt : 1.3.0
xlsxwriter : 1.2.7
numba : 0.48.0

[rockg]

See #8435. The code assumes quarters start on month 3 (so 3, 6, 9, 12). Just pass in startingMonth=1 to get the behaviour you are after.

[simonjayhawkins]

Thanks @patrickxli for the report. closing as duplicate of #8435