Remove unreachable content length check for chunked encoding

[bdraco]

_prepare_headers had a check to remove content-length if chunked encoding was set. This code was unreachable under normal circumstances because enabling chunked encoding checks to see if the content-length header is there and raises RuntimeError. It was still possible to reach this code if RuntimeError was suppressed because enable_chunked_encoding set self._chunked = True before checking if it needed to raise. To make it truly unreachable, the check is now done first in enable_chunked_encoding

[codspeed-hq]

CodSpeed Performance Report

Merging #10058 will not alter performance

_{Comparing unreachable_cl_check (ba686c8) with master (11f0e7f)}

Summary

✅ 44 untouched benchmarks

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.75%. Comparing base (11f0e7f) to head (ba686c8).
Report is 1 commits behind head on master.

✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #10058   +/-   ##
=======================================
  Coverage   98.75%   98.75%           
=======================================
  Files         121      121           
  Lines       36789    36787    -2     
  Branches     4395     4394    -1     
=======================================
  Hits        36330    36330           
+ Misses        312      311    -1     
+ Partials      147      146    -1     

Flag	Coverage Δ
CI-GHA	98.64% <100.00%> (+<0.01%)	⬆️
OS-Linux	98.33% <100.00%> (+<0.01%)	⬆️
OS-Windows	96.17% <100.00%> (+<0.01%)	⬆️
OS-macOS	97.43% <100.00%> (+<0.01%)	⬆️
Py-3.10.11	97.28% <100.00%> (+<0.01%)	⬆️
Py-3.10.15	97.82% <100.00%> (+<0.01%)	⬆️
Py-3.11.10	97.86% <100.00%> (-0.01%)	⬇️
Py-3.11.9	97.33% <100.00%> (-0.01%)	⬇️
Py-3.12.7	98.39% <100.00%> (-0.01%)	⬇️
Py-3.13.0	98.38% <100.00%> (-0.01%)	⬇️
Py-3.9.13	97.20% <100.00%> (+<0.01%)	⬆️
Py-3.9.20	97.74% <100.00%> (+<0.01%)	⬆️
Py-pypy7.3.16	97.35% <100.00%> (+<0.01%)	⬆️
VM-macos	97.43% <100.00%> (+<0.01%)	⬆️
VM-ubuntu	98.33% <100.00%> (+<0.01%)	⬆️
VM-windows	96.17% <100.00%> (+<0.01%)	⬆️

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[patchback]

Backport to 3.11: 💔 cherry-picking failed — conflicts found

❌ Failed to cleanly apply 12372d7 on top of patchback/backports/3.11/12372d7fe06d95c1c633a3b8119aecf4e86cf94d/pr-10058

Backporting merged PR #10058 into master

1. Ensure you have a local repo clone of your fork. Unless you cloned it
   from the upstream, this would be your origin remote.
2. Make sure you have an upstream repo added as a remote too. In these
   instructions you'll refer to it by the name upstream. If you don't
   have it, here's how you can add it:

   $ git remote add upstream https://github.com/aio-libs/aiohttp.git

3. Ensure you have the latest copy of upstream and prepare a branch
   that will hold the backported code:

   $ git fetch upstream
   $ git checkout -b patchback/backports/3.11/12372d7fe06d95c1c633a3b8119aecf4e86cf94d/pr-10058 upstream/3.11

4. Now, cherry-pick PR Remove unreachable content length check for chunked encoding #10058 contents into that branch:

   $ git cherry-pick -x 12372d7fe06d95c1c633a3b8119aecf4e86cf94d

   If it'll yell at you with something like fatal: Commit 12372d7fe06d95c1c633a3b8119aecf4e86cf94d is a merge but no -m option was given., add -m 1 as follows instead:

   $ git cherry-pick -m1 -x 12372d7fe06d95c1c633a3b8119aecf4e86cf94d

5. At this point, you'll probably encounter some merge conflicts. You must
   resolve them in to preserve the patch from PR Remove unreachable content length check for chunked encoding #10058 as close to the
   original as possible.
6. Push this branch to your fork on GitHub:

   $ git push origin patchback/backports/3.11/12372d7fe06d95c1c633a3b8119aecf4e86cf94d/pr-10058

7. Create a PR, ensure that the CI is green. If it's not — update it so that
   the tests and any other checks pass. This is it!
   Now relax and wait for the maintainers to process your pull request
   when they have some cycles to do reviews. Don't worry — they'll tell you if
   any improvements are necessary when the time comes!

🤖 @patchback
I'm built with octomachinery and
my source is open — https://github.com/sanitizers/patchback-github-app.

[patchback]

Backport to 3.12: 💔 cherry-picking failed — conflicts found

❌ Failed to cleanly apply 12372d7 on top of patchback/backports/3.12/12372d7fe06d95c1c633a3b8119aecf4e86cf94d/pr-10058

Backporting merged PR #10058 into master

1. Ensure you have a local repo clone of your fork. Unless you cloned it
   from the upstream, this would be your origin remote.
2. Make sure you have an upstream repo added as a remote too. In these
   instructions you'll refer to it by the name upstream. If you don't
   have it, here's how you can add it:

   $ git remote add upstream https://github.com/aio-libs/aiohttp.git

3. Ensure you have the latest copy of upstream and prepare a branch
   that will hold the backported code:

   $ git fetch upstream
   $ git checkout -b patchback/backports/3.12/12372d7fe06d95c1c633a3b8119aecf4e86cf94d/pr-10058 upstream/3.12

4. Now, cherry-pick PR Remove unreachable content length check for chunked encoding #10058 contents into that branch:

   $ git cherry-pick -x 12372d7fe06d95c1c633a3b8119aecf4e86cf94d

   If it'll yell at you with something like fatal: Commit 12372d7fe06d95c1c633a3b8119aecf4e86cf94d is a merge but no -m option was given., add -m 1 as follows instead:

   $ git cherry-pick -m1 -x 12372d7fe06d95c1c633a3b8119aecf4e86cf94d

5. At this point, you'll probably encounter some merge conflicts. You must
   resolve them in to preserve the patch from PR Remove unreachable content length check for chunked encoding #10058 as close to the
   original as possible.
6. Push this branch to your fork on GitHub:

   $ git push origin patchback/backports/3.12/12372d7fe06d95c1c633a3b8119aecf4e86cf94d/pr-10058

7. Create a PR, ensure that the CI is green. If it's not — update it so that
   the tests and any other checks pass. This is it!
   Now relax and wait for the maintainers to process your pull request
   when they have some cycles to do reviews. Don't worry — they'll tell you if
   any improvements are necessary when the time comes!

🤖 @patchback
I'm built with octomachinery and
my source is open — https://github.com/sanitizers/patchback-github-app.