No default Content-Type when no content

[Dreamsorcerer]

Fixes #4612.

Minor typing cleanup included as well.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.24%. Comparing base (faa15fd) to head (4d8bafb).
Report is 1071 commits behind head on master.

✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #8858   +/-   ##
=======================================
  Coverage   98.24%   98.24%           
=======================================
  Files         107      107           
  Lines       34107    34122   +15     
  Branches     4050     4053    +3     
=======================================
+ Hits        33507    33522   +15     
  Misses        424      424           
  Partials      176      176           

Flag	Coverage Δ
CI-GHA	98.13% <100.00%> (+<0.01%)	⬆️
OS-Linux	97.79% <100.00%> (+<0.01%)	⬆️
OS-Windows	96.18% <100.00%> (+<0.01%)	⬆️
OS-macOS	97.47% <100.00%> (+<0.01%)	⬆️
Py-3.10.11	97.55% <100.00%> (-0.01%)	⬇️
Py-3.10.14	97.49% <100.00%> (+<0.01%)	⬆️
Py-3.11.9	97.72% <100.00%> (-0.01%)	⬇️
Py-3.12.4	95.98% <100.00%> (+<0.01%)	⬆️
Py-3.12.5	97.52% <100.00%> (+<0.01%)	⬆️
Py-3.9.13	97.45% <100.00%> (+<0.01%)	⬆️
Py-3.9.19	97.39% <100.00%> (+<0.01%)	⬆️
Py-pypy7.3.16	96.99% <100.00%> (+<0.01%)	⬆️
VM-macos	97.47% <100.00%> (+<0.01%)	⬆️
VM-ubuntu	97.79% <100.00%> (+<0.01%)	⬆️
VM-windows	96.18% <100.00%> (+<0.01%)	⬆️

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[patchback]

Backport to 3.10: 💔 cherry-picking failed — conflicts found

❌ Failed to cleanly apply 26772ad on top of patchback/backports/3.10/26772ad320c1ee0efa5b91ae35ae5860a37cd709/pr-8858

Backporting merged PR #8858 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/3.10/26772ad320c1ee0efa5b91ae35ae5860a37cd709/pr-8858 upstream/3.10

4. Now, cherry-pick PR No default Content-Type when no content #8858 contents into that branch:

   $ git cherry-pick -x 26772ad320c1ee0efa5b91ae35ae5860a37cd709

   If it'll yell at you with something like fatal: Commit 26772ad320c1ee0efa5b91ae35ae5860a37cd709 is a merge but no -m option was given., add -m 1 as follows instead:

   $ git cherry-pick -m1 -x 26772ad320c1ee0efa5b91ae35ae5860a37cd709

5. At this point, you'll probably encounter some merge conflicts. You must
   resolve them in to preserve the patch from PR No default Content-Type when no content #8858 as close to the
   original as possible.
6. Push this branch to your fork on GitHub:

   $ git push origin patchback/backports/3.10/26772ad320c1ee0efa5b91ae35ae5860a37cd709/pr-8858

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 3.11: 💔 cherry-picking failed — conflicts found

❌ Failed to cleanly apply 26772ad on top of patchback/backports/3.11/26772ad320c1ee0efa5b91ae35ae5860a37cd709/pr-8858

Backporting merged PR #8858 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/3.11/26772ad320c1ee0efa5b91ae35ae5860a37cd709/pr-8858 upstream/3.11

4. Now, cherry-pick PR No default Content-Type when no content #8858 contents into that branch:

   $ git cherry-pick -x 26772ad320c1ee0efa5b91ae35ae5860a37cd709

   If it'll yell at you with something like fatal: Commit 26772ad320c1ee0efa5b91ae35ae5860a37cd709 is a merge but no -m option was given., add -m 1 as follows instead:

   $ git cherry-pick -m1 -x 26772ad320c1ee0efa5b91ae35ae5860a37cd709

5. At this point, you'll probably encounter some merge conflicts. You must
   resolve them in to preserve the patch from PR No default Content-Type when no content #8858 as close to the
   original as possible.
6. Push this branch to your fork on GitHub:

   $ git push origin patchback/backports/3.11/26772ad320c1ee0efa5b91ae35ae5860a37cd709/pr-8858

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.