Add trailer parsing logic (#11269)

[Dreamsorcerer]

(cherry picked from commit 7dd4b55)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.30%. Comparing base (0389371) to head (2420eac).
Report is 1 commits behind head on 3.12.

✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             3.12   #11287      +/-   ##
==========================================
- Coverage   98.31%   98.30%   -0.02%     
==========================================
  Files         132      132              
  Lines       43506    43502       -4     
  Branches     2380     2379       -1     
==========================================
- Hits        42775    42765      -10     
- Misses        555      561       +6     
  Partials      176      176              

Flag	Coverage Δ
CI-GHA	98.20% <100.00%> (-0.02%)	⬇️
OS-Linux	97.94% <100.00%> (-0.02%)	⬇️
OS-Windows	95.66% <98.14%> (+<0.01%)	⬆️
OS-macOS	97.20% <98.14%> (-0.01%)	⬇️
Py-3.10.11	96.84% <98.14%> (-0.01%)	⬇️
Py-3.10.18	97.33% <100.00%> (-0.01%)	⬇️
Py-3.11.13	97.52% <100.00%> (-0.01%)	⬇️
Py-3.11.9	97.04% <98.14%> (+<0.01%)	⬆️
Py-3.12.10	97.13% <98.14%> (-0.01%)	⬇️
Py-3.12.11	97.62% <100.00%> (-0.01%)	⬇️
Py-3.13.3	97.86% <100.00%> (-0.01%)	⬇️
Py-3.9.13	96.74% <98.14%> (-0.01%)	⬇️
Py-3.9.23	97.22% <100.00%> (-0.01%)	⬇️
Py-pypy7.3.16	94.09% <100.00%> (+6.14%)	⬆️
VM-macos	97.20% <98.14%> (-0.01%)	⬇️
VM-ubuntu	97.94% <100.00%> (-0.02%)	⬇️
VM-windows	95.66% <98.14%> (+<0.01%)	⬆️

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[codspeed-hq]

CodSpeed Performance Report

Merging #11287 will not alter performance

_{Comparing patchback/backports/3.12/7dd4b5535e6bf9c2d2f05fde638517bff065ba74/pr-11269 (2420eac) with 3.12 (0389371)}

Summary

✅ 59 untouched benchmarks