bpo-31639: Change ThreadedHTTPServer to ThreadingHTTPServer class name

[geryogam]

Changes the class name http.server.ThreadedHTTPServer to http.server.ThreadingHTTPServer introduced by @JulienPalard on 23 March 2018 for Python 3.7, in order to be consistent with the already existing classes:

• socketserver.ForkingTCPServer;
• socketserver.ForkingUDPServer;
• socketserver.ThreadingTCPServer;
• socketserver.ThreadingUDPServer.

https://bugs.python.org/issue31639

[JulienPalard]

LGTM, it make sense, but can probably only be merged before 3.7.0, as changing it after would mean breaking compatibility.

[vstinner]

LGTM if and only if the change is merged into 3.7 before 3.7 final.

The change doesn't break the backward compatibility because the renamed class has been introduced in Python 3.7 which is not released yet (beta versions have been released, but not the 3.7.0 final).

[miss-islington]

Thanks @maggyero for the PR, and @JulienPalard for merging it 🌮🎉.. I'm working now to backport this PR to: 3.7.
🐍🍒⛏🤖

[miss-islington]

Sorry, @maggyero and @JulienPalard, I could not cleanly backport this to 3.7 due to a conflict.
Please backport using cherry_picker on command line.
cherry_picker 1cee216cf383eade641aed22f4ec7d4cb565ecff 3.7

[elprans]

You forgot to update the entry in What's New.

[bedevere-bot]

GH-7219 is a backport of this pull request to the 3.7 branch.

[JulienPalard]

@elprans Hey thanks for noticing, I'm fixing it and will backport both in the same PR in 3.7.

[geryogam]

@JulienPalard Thanks for the merge.