BUG:

[shadowbourne]

---

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

Code Sample, a copy-pastable example

# Your code here
import pandas as pd
def edit(row):
    row["poo"] = 9
    return row
df = pd.DataFrame({"foo":[1,2,3,4],"Hi":[0,1,0,2]})
print(df.head())
print(df.apply(edit, axis=1))

Problem description

Returns completely wrong output on my system, but anyone else's it seems fine. (pandas 1.1.0, python 3.8.4 and 3.7.8)
[this should explain why the current behaviour is a problem and why the expected output is a better solution]

Bugged Output:

foo Hi poo
0 1 0 9
1 1 0 9
2 1 0 9
3 1 0 9

Expected Output

foo Hi poo
0 1 0 9
1 2 1 9
2 3 0 9
3 4 2 9

Output of pd.show_versions()

INSTALLED VERSIONS ------------------ commit : d9fff27 python : 3.7.8.final.0 python-bits : 64 OS : Windows OS-release : 10 Version : 10.0.18362 machine : AMD64 processor : AMD64 Family 21 Model 2 Stepping 0, AuthenticAMD byteorder : little LC_ALL : None LANG : en_GB.UTF-8 LOCALE : None.None

pandas : 1.1.0
numpy : 1.19.1
pytz : 2020.1
dateutil : 2.8.1
pip : 20.1.1
setuptools : 47.1.0
Cython : None
pytest : None
hypothesis : None
sphinx : None
blosc : None
feather : None
xlsxwriter : None
lxml.etree : None
html5lib : None
pymysql : None
psycopg2 : None
jinja2 : None
IPython : None
pandas_datareader: None
bs4 : None
bottleneck : None
fsspec : None
fastparquet : None
gcsfs : None
matplotlib : None
numexpr : None
odfpy : None
openpyxl : None
pandas_gbq : None
pyarrow : None
pytables : None
pyxlsb : None
s3fs : None
scipy : None
sqlalchemy : None
tables : None
tabulate : None
xarray : None
xlrd : None
xlwt : None
numba : None
None
[paste the output of pd.show_versions() here leaving a blank line after the details tag]

[simonjayhawkins]

Thanks @shadowbourne for the report. This is a duplicate of #35462 so closing.