gh-151485: Fix command quoting in subprocess.CalledProcessError.__str__

[BenjyWiener]

subprocess.CalledProcessError.__str__ previously formatted cmd as "... '%s' ...". This lead to unbalanced quoting when cmd contains single-quotes or, more commonly, when cmd is a list. This change updates the relevant format strings to use %r instead.

In terms of backwards compatibility, the only impact I anticipate is on doctests, and I suspect doctests for subprocess.CalledProcessError to be quite rare.

Before this PR:

>>> import subprocess
>>> subprocess.check_call(['false'])
Traceback (most recent call last):
  ...
subprocess.CalledProcessError: Command '['false']' returned non-zero exit status 1.

After:

>>> import subprocess
>>> subprocess.check_call(['false'])
Traceback (most recent call last):
  ...
subprocess.CalledProcessError: Command ['false'] returned non-zero exit status 1.

• Issue: subprocess.CalledProcessError misquotes list-style commands #151485

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[vstinner]

Can you please add a test to test_subprocess?

[vstinner]

LGTM

[vstinner]

Tests / Sanitizers / TSan (free-threading) (pull_request): Cancelled after 60m

Ah, the job was cancelled, test_abc seems to be stuck:

Run ./python -m test --tsan-parallel --parallel-threads=4 -j4 -W
Using random seed: 2157163694
0:00:00 load avg: 2.93 mem: 274.0 MiB Run 2 tests in parallel using 2 worker processes
0:00:12 load avg: 3.10 mem: 591.6 MiB [1/2] test_hashlib passed
0:00:42 load avg: 1.88 mem: 591.6 MiB running (1): test_abc (42.3 sec)
0:01:13 load avg: 1.14 mem: 591.7 MiB running (1): test_abc (1 min 12 sec)
...
0:37:00 load avg: 0.01 mem: 533.8 MiB running (1): test_abc (36 min 59 sec)
Error: The operation was canceled.

[vstinner]

Ah, the job was cancelled, test_abc seems to be stuck

I created #151593 to investigate this test_abc issue.

[python-cla-bot]

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[vstinner]

Merged, thanks for the fix. I don't think that it should be backported since it can impact tests relying on the exact str(exc).

[BenjyWiener]

Thanks! Out of curiosity, what's the policy for fixes like these when it comes to beta releases?

[vstinner]

Thanks! Out of curiosity, what's the policy for fixes like these when it comes to beta releases?

After the feature freeze (beta1), new features and backward incompatible changes are no longer accepted (in the 3.15 branch).