Fix double compress when compression enabled and compressed file exists

[bdraco]

What do these changes do?

If the handler has .enable_compression set and we use the pre-compressed .gz we would compress twice. The caller may not know if the .gz file exists or not or have a mixed use case where some files are pre-compressed and some are compressed on the fly based if they have limited storage

fixes #8011

Are there changes in behavior for the user?

Files are no longer double compressed which is likely never the desired outcome

Related issue number

Checklist

• I think the code is well written
• Unit tests for the changes exist
• Documentation reflects the changes
• If you provide code modification, please add yourself to CONTRIBUTORS.txt
  • The format is <Name> <Surname>.
  • Please keep alphabetical order, the file is sorted by names.
• Add a new news fragment into the CHANGES folder
  • name it <issue_id>.<type> for example (588.bugfix)
  • if you don't have an issue_id change it to the pr id after creating the pr
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    • .feature: Signifying a new feature.
    • .bugfix: Signifying a bug fix.
    • .doc: Signifying a documentation improvement.
    • .removal: Signifying a deprecation or removal of public API.
    • .misc: A ticket has been closed, but it is not of interest to users.
  • Make sure to use full sentences with correct case and punctuation, for example: "Fix issue with non-ascii contents in doctest text files."

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (5f699bb) 97.46% compared to head (0965604) 97.46%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #8014   +/-   ##
=======================================
  Coverage   97.46%   97.46%           
=======================================
  Files         107      107           
  Lines       32529    32548   +19     
  Branches     3790     3790           
=======================================
+ Hits        31703    31722   +19     
  Misses        624      624           
  Partials      202      202           

Flag	Coverage Δ
CI-GHA	97.37% <100.00%> (+<0.01%)	⬆️
OS-Linux	97.05% <100.00%> (+<0.01%)	⬆️
OS-Windows	95.55% <100.00%> (+<0.01%)	⬆️
OS-macOS	96.86% <100.00%> (+0.18%)	⬆️
Py-3.10.11	95.47% <100.00%> (+<0.01%)	⬆️
Py-3.10.13	96.85% <100.00%> (+<0.01%)	⬆️
Py-3.11.7	96.60% <100.00%> (+0.02%)	⬆️
Py-3.12.1	96.67% <100.00%> (+0.02%)	⬆️
Py-3.8.10	95.44% <100.00%> (+<0.01%)	⬆️
Py-3.8.18	96.79% <100.00%> (+<0.01%)	⬆️
Py-3.9.13	95.44% <100.00%> (+<0.01%)	⬆️
Py-3.9.18	96.82% <100.00%> (-0.01%)	⬇️
Py-pypy7.3.14	96.38% <100.00%> (+<0.01%)	⬆️
VM-macos	96.86% <100.00%> (+0.18%)	⬆️
VM-ubuntu	97.05% <100.00%> (+<0.01%)	⬆️
VM-windows	95.55% <100.00%> (+<0.01%)	⬆️

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[patchback]

Backport to 3.9: 💔 cherry-picking failed — conflicts found

❌ Failed to cleanly apply 92655a5 on top of patchback/backports/3.9/92655a50987e8bdfb6241dabbedc4c3cc8f55272/pr-8014

Backporting merged PR #8014 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/3.9/92655a50987e8bdfb6241dabbedc4c3cc8f55272/pr-8014 upstream/3.9

4. Now, cherry-pick PR Fix double compress when compression enabled and compressed file exists #8014 contents into that branch:

   $ git cherry-pick -x 92655a50987e8bdfb6241dabbedc4c3cc8f55272

   If it'll yell at you with something like fatal: Commit 92655a50987e8bdfb6241dabbedc4c3cc8f55272 is a merge but no -m option was given., add -m 1 as follows instead:

   $ git cherry-pick -m1 -x 92655a50987e8bdfb6241dabbedc4c3cc8f55272

5. At this point, you'll probably encounter some merge conflicts. You must
   resolve them in to preserve the patch from PR Fix double compress when compression enabled and compressed file exists #8014 as close to the
   original as possible.
6. Push this branch to your fork on GitHub:

   $ git push origin patchback/backports/3.9/92655a50987e8bdfb6241dabbedc4c3cc8f55272/pr-8014

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 3.10: 💔 cherry-picking failed — conflicts found

❌ Failed to cleanly apply 92655a5 on top of patchback/backports/3.10/92655a50987e8bdfb6241dabbedc4c3cc8f55272/pr-8014

Backporting merged PR #8014 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/3.10/92655a50987e8bdfb6241dabbedc4c3cc8f55272/pr-8014 upstream/3.10

4. Now, cherry-pick PR Fix double compress when compression enabled and compressed file exists #8014 contents into that branch:

   $ git cherry-pick -x 92655a50987e8bdfb6241dabbedc4c3cc8f55272

   If it'll yell at you with something like fatal: Commit 92655a50987e8bdfb6241dabbedc4c3cc8f55272 is a merge but no -m option was given., add -m 1 as follows instead:

   $ git cherry-pick -m1 -x 92655a50987e8bdfb6241dabbedc4c3cc8f55272

5. At this point, you'll probably encounter some merge conflicts. You must
   resolve them in to preserve the patch from PR Fix double compress when compression enabled and compressed file exists #8014 as close to the
   original as possible.
6. Push this branch to your fork on GitHub:

   $ git push origin patchback/backports/3.10/92655a50987e8bdfb6241dabbedc4c3cc8f55272/pr-8014

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.

[steverep]

If the client makes a request for "/hello.txt.gz" and the handler enables compression, what should the expected response be? Is it intentional that that would still result in double compression?