[3.7] Don't cancel web handler on disconnection (#4080)

[Jackenmen]

What do these changes do?

Backport #4080 to aiohttp 3.7. I'm not sure whether there's gonna be another 3.6 release or if 3.7 is still planned but this allows to handle connections issues properly so would be good to have.

Are there changes in behavior for the user?

ConnectionResetError is raised on writing to closing transport instead of a warning.

Related issue number

#4080

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
  • ensure type is one of the following:
    • .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-commenter]

Codecov Report

Merging #4771 into 3.7 will increase coverage by 0.38%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##              3.7    #4771      +/-   ##
==========================================
+ Coverage   97.56%   97.94%   +0.38%     
==========================================
  Files          44       44              
  Lines        8953     8964      +11     
  Branches     1408     1410       +2     
==========================================
+ Hits         8735     8780      +45     
+ Misses        110       78      -32     
+ Partials      108      106       -2     

Impacted Files	Coverage Δ
aiohttp/http_websocket.py	98.67% <100.00%> (+0.01%)	⬆️
aiohttp/web_protocol.py	91.94% <100.00%> (+1.36%)	⬆️
aiohttp/web_request.py	97.53% <100.00%> (+0.01%)	⬆️
aiohttp/helpers.py	96.50% <0.00%> (+0.50%)	⬆️
aiohttp/pytest_plugin.py	97.57% <0.00%> (+1.81%)	⬆️
aiohttp/http_writer.py	99.05% <0.00%> (+3.77%)	⬆️
aiohttp/http_parser.py	97.24% <0.00%> (+4.81%)	⬆️

---

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[codecov-io]

Codecov Report

Merging #4771 into 3.7 will decrease coverage by 0.35%.
The diff coverage is 95.65%.

@@            Coverage Diff             @@
##              3.7    #4771      +/-   ##
==========================================
- Coverage   97.62%   97.27%   -0.36%     
==========================================
  Files          44       44              
  Lines        9020     9033      +13     
  Branches     1419     1422       +3     
==========================================
- Hits         8806     8787      -19     
- Misses         95      124      +29     
- Partials      119      122       +3     

Flag	Coverage Δ
#unit	97.27% <95.65%> (-0.36%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
aiohttp/web_protocol.py	91.69% <90.90%> (+1.11%)	⬆️
aiohttp/http_websocket.py	98.67% <100.00%> (+0.01%)	⬆️
aiohttp/web_request.py	97.54% <100.00%> (+0.01%)	⬆️
aiohttp/web_runner.py	91.94% <0.00%> (-5.69%)	⬇️
aiohttp/pytest_plugin.py	92.72% <0.00%> (-4.85%)	⬇️
aiohttp/tcp_helpers.py	90.00% <0.00%> (-3.34%)	⬇️
aiohttp/connector.py	94.67% <0.00%> (-1.89%)	⬇️
aiohttp/test_utils.py	98.75% <0.00%> (-0.63%)	⬇️

---

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[asvetlov]

Thanks!