Accept case-insensitive range unit names in Range header

[afonsojanu]

Closes #13580.

RFC 9110 section 14.1.1 states that range unit names are case-insensitive, but the regex used to parse the Range header only matched a lowercase bytes literal:

pattern = r"^bytes=(\d*)-(\d*)$"
start, end = re.findall(pattern, rng, re.ASCII)[0]

A request sent with any other casing, such as Range: Bytes=0-3 or Range: BYTES=0-3, raised ValueError("range not in acceptable format"), which FileResponse turns into a 416 response even though the range itself is perfectly satisfiable.

Added re.IGNORECASE to the existing pattern match flags and a regression test alongside the existing range-parsing tests, covering an uppercase-initial unit name. Ran the full test_web_request.py suite plus flake8 on the touched files.

[greptile-apps]

Confidence Score: 5/5

The PR appears safe to merge with no actionable correctness, compatibility, or security issues identified.

The parser remains anchored to the bytes unit and ASCII digits, while the only behavioral expansion is accepting RFC-compliant ASCII case variants; existing invalid-input and FileResponse error behavior remain intact.

_{Reviews (1): Last reviewed commit: "Accept case-insensitive range unit names..." | Re-trigger Greptile}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.02%. Comparing base (20acdf4) to head (0393b9e).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #13585   +/-   ##
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  Coverage   99.02%   99.02%           
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  Files         135      135           
  Lines       50500    50504    +4     
  Branches     2652     2652           
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+ Hits        50007    50011    +4     
  Misses        370      370           
  Partials      123      123           

Flag	Coverage Δ
Autobahn	22.03% <20.00%> (+<0.01%)	⬆️
CI-GHA	98.91% <100.00%> (+<0.01%)	⬆️
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OS-macOS	97.96% <100.00%> (-0.01%)	⬇️
Py-3.10	98.11% <100.00%> (+<0.01%)	⬆️
Py-3.11	98.34% <100.00%> (+<0.01%)	⬆️
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Py-3.14	98.44% <100.00%> (-0.01%)	⬇️
Py-3.14t	97.60% <100.00%> (-0.01%)	⬇️
Py-pypy-3.11	97.40% <100.00%> (+0.01%)	⬆️
VM-macos	97.96% <100.00%> (-0.01%)	⬇️
VM-ubuntu	98.68% <100.00%> (+<0.01%)	⬆️
VM-windows	97.09% <100.00%> (+<0.01%)	⬆️
cython-coverage	83.07% <0.00%> (ø)

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[codspeed-hq]

Merging this PR will not alter performance

✅ 96 untouched benchmarks
⏩ 83 skipped benchmarks¹

---

_{Comparing afonsojanu:fix/http-range-case-insensitive-unit-13580 (0393b9e) with master (20acdf4)}

Footnotes

1. 83 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. ↩