Http exception cookies support

[derlih]

What do these changes do?

Add methods set_cookie() an del_cookie() to HTTPException
Add cookies property to HTTPException

Are there changes in behavior for the user?

User can set the cookies for HTTPException

Related issue number

#4277

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]

Codecov Report

Merging #5197 (b617eb5) into master (7ebc07a) will decrease coverage by 0.01%.
The diff coverage is 96.00%.

@@            Coverage Diff             @@
##           master    #5197      +/-   ##
==========================================
- Coverage   97.56%   97.54%   -0.02%     
==========================================
  Files          43       43              
  Lines        8779     8794      +15     
  Branches     1412     1413       +1     
==========================================
+ Hits         8565     8578      +13     
- Misses        100      101       +1     
- Partials      114      115       +1     

Flag	Coverage Δ
unit	97.39% <96.00%> (-0.02%)	⬇️

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Impacted Files	Coverage Δ
aiohttp/resolver.py	93.18% <ø> (ø)
aiohttp/helpers.py	96.55% <95.23%> (-0.14%)	⬇️
aiohttp/web_exceptions.py	99.52% <100.00%> (+<0.01%)	⬆️
aiohttp/web_protocol.py	92.28% <100.00%> (+0.02%)	⬆️
aiohttp/web_response.py	98.09% <100.00%> (+0.29%)	⬆️
aiohttp/streams.py	97.43% <0.00%> (-0.49%)	⬇️

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[derlih]

@asvetlov if this approach is OK, I will update the documentation.

[asvetlov]

Looks good.
Could you please update web_excetions.rst to reflect new methods?

[derlih]

What versionadded should I use to reflect these changes in documentation?

[asvetlov]

4.0
In 3.x branch HTTPException is derived from Response, thus it has cookie methods already.
Let's add breaking changes in major releases only.

[derlih]

That was exactly the reason why I've raised my question. If it doesn't break the API from 3.x in theory it can be backported to 3.x.

[asvetlov]

Dropping the inheritance from web.Response is not backward compatible change.

While we keep the inheritance -- there Is no need to backport this PR because web.Response already provides the cookies API

[asvetlov]

Thanks!