BUG: NonExistentTimeError with resample("7D"), but only when DST day is not part of the date range

[kdebrab]

Pandas version checks

• I have checked that this issue has not already been reported.

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

• I have confirmed this bug exists on the main branch of pandas.

Reproducible Example

import pandas as pd

ts = pd.Series(1, pd.date_range("2024-04-19", "2024-04-20", tz="Africa/Cairo", freq="15min"))
ts.resample("7D").sum()

Issue Description

Above fails with pytz.exceptions.NonExistentTimeError: 2024-04-26 00:00:00 even though that date falls outside the date range.

Strangely, when the end date is later, and thus the problematic date is included in the result, it doesn't fail anymore:

ts = pd.Series(1, pd.date_range("2024-04-19", "2024-04-27", tz="Africa/Cairo", freq="15min"))
ts.resample("7D").sum()

returns:

2024-04-19 00:00:00+02:00    672
2024-04-26 01:00:00+03:00     93
Freq: 7D, dtype: int64

Expected Behavior

No failure and the correct result, namely:

2024-04-19 00:00:00+02:00    97
Freq: 7D, dtype: int64

Installed Versions

INSTALLED VERSIONS

commit : d9cdd2e
python : 3.10.4.final.0
python-bits : 64
OS : Windows
OS-release : 10
Version : 10.0.19045
machine : AMD64
processor : Intel64 Family 6 Model 140 Stepping 1, GenuineIntel
byteorder : little
LC_ALL : None
LANG : None
LOCALE : English_Belgium.1252
pandas : 2.2.2
numpy : 1.26.4
pytz : 2024.1
dateutil : 2.9.0.post0
setuptools : 69.5.1
pip : 23.3.1
Cython : None
pytest : 7.4.2
hypothesis : None
sphinx : None
blosc : None
feather : None
xlsxwriter : 3.1.2
lxml.etree : 5.2.1
html5lib : None
pymysql : None
psycopg2 : None
jinja2 : 3.1.3
IPython : 8.4.0
pandas_datareader : None
adbc-driver-postgresql: None
adbc-driver-sqlite : None
bs4 : None
bottleneck : 1.3.8
dataframe-api-compat : None
fastparquet : 2023.2.0
fsspec : 2024.3.1
gcsfs : None
matplotlib : 3.7.5
numba : None
numexpr : 2.10.0
odfpy : None
openpyxl : 3.1.2
pandas_gbq : None
pyarrow : 15.0.2
pyreadstat : None
python-calamine : None
pyxlsb : None
s3fs : None
scipy : 1.13.0
sqlalchemy : 2.0.28
tables : None
tabulate : 0.9.0
xarray : 2024.3.0
xlrd : None
zstandard : None
tzdata : 2024.1
qtpy : None
pyqt5 : None

[MarognaLorenzo]

take

[kdebrab]

FYI, the same error happens when resampling to daily resolution when the last day is the day before the DST:

ts = pd.Series(1, pd.date_range("2024-04-19", "2024-04-25", tz="Africa/Cairo", freq="15min"))
ts.resample("D").sum()

It doesn't fail anymore as soon as the end is later, e.g.:

ts = pd.Series(1, pd.date_range("2024-04-19", "2024-04-27", tz="Africa/Cairo", freq="15min"))
ts.resample("D").sum()