traceback shows wrong source code in basic REPL when PYTHONSTARTUP is set

[ilupin]

Bug report

Bug description:

Start python with the basic repl and a PYTHONSTARTUP file

export PYTHON_BASIC_REPL=1; echo 'import math' > /tmp/foo.py; export PYTHONSTARTUP="/tmp/foo.py"; python

type 1/0 and the traceback shows

Python 3.13.5 | packaged by Anaconda, Inc. | (main, Jun 12 2025, 16:09:02) [GCC 11.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> 1/0
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
    import math
    ^^^
ZeroDivisionError: division by zero
>>> 

Expected behavior (i.e. export PYTHON_BASIC_REPL=1; unset PYTHONSTARTUP; python):

>>> 1/0
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
    1/0
    ~^~
ZeroDivisionError: division by zero
>>>

CPython versions tested on:

3.13

Operating systems tested on:

Linux

Linked PRs

• gh-137576: Fix for Basic REPL Showing Incorrect Code in Tracebacks with PYTHONSTARTUP #137625

[StanFromIreland]

Note that the new pyrepl is not affected.

$ echo 'import math' > /tmp/foo.py; export PYTHONSTARTUP="/tmp/foo.py"; python3.15
Python 3.15.0a0 (heads/main:d7e12a362a2, Jul 29 2025, 09:10:09) [GCC 15.1.1 20250521 (Red Hat 15.1.1-2)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> 1/0
Traceback (most recent call last):
  File "<python-input-0>", line 1, in <module>
    1/0
    ~^~
ZeroDivisionError: division by zero
>>>

[adqm]

I think I have a fix for this; I'll put in a PR later this evening.