[zaniebot]

When a Python download URL does not match the upstream format expected by a custom mirror, the error repeats the mirror environment variable instead of showing the offending URL. Display the URL in that diagnostic and store it as a DisplaySafeUrl so passwords and sensitive query parameters are redacted. Malformed source URLs use the existing InvalidUrl error.

[codspeed]

Merging this PR will not alter performance

✅ 54 untouched benchmarks
⏩ 35 skipped benchmarks¹

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_{Comparing zb/python-mirror-error-url (f42ee29) with main (cea939e)}

Footnotes

1. 35 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[astral-automations-bot]

Promoted to #22364.