SIGSEV in `datetime.timedelta` (possibly from datetime's C `delta_new`)

Crash report

What happened?

I was testing some AI code with ollama and stumbled across a really weird crash.
The fact that it happens during an IndexError and a specific function has to be there leads me to believe that this is a CPython bug and not an ollama bug.

from ollama import chat

# Has to be here to segfault???
def colorSwitch(color): 
    print(color, end="", flush=True)


stream = chat(
    model="llama3.2", # I think it works with any but this is what I used.
    messages=[{"role": "user", "content": ""}],
    options={"seed":0}, # Does not need this but I figured it would be helpful
    stream=True,
)
# Any iteration works. I just simplified it down to this.
part = next(iter(stream))['message']['content']
temp = part.split("</think>", 1)

# Crash Here
temp[1]

PythonCore.zip

CPython versions tested on:

3.13

Operating systems tested on:

Linux

Output from running 'python -VV' on the command line:

Python 3.13.2 (main, Feb 5 2025, 08:05:21) [GCC 14.2.1 20250128]

Linked PRs

• gh-132599
• gh-132665
• gh-133111
• gh-136152
• gh-136321

Start with the minimal reproducer in the issue and read the linked PRs gh-132599, gh-132665, gh-133111, gh-136152, and gh-136321. Then inspect the datetime C delta_new path named in the report. Done means the Python 3.13 reproducer no longer causes a SIGSEV on Linux.