urlsplit manufactures hostnames because it strips off tabs before validating them

Bug report

Bug description:

import urllib.parse

# prints "abcxyz.test"
print(urllib.parse.urlsplit("http://abc\txyz.test/").netloc)

Current urlsplit is implemented according to this spec:

https://url.spec.whatwg.org/#concept-basic-url-parser

The spec does say in item 3 to strip tabs, but I believe there's a bug in the specification (perhaps they wanted to say leading/trailing whitespace) because the item 7 in host parsing says

If asciiDomain contains a forbidden domain code point, domain-invalid-code-point validation error, return failure.

, and tab is listed as a "forbidden domain code point". If tabs are stripped from the entire input before any other work is done, checking for tabs in host names wouldn't make much sense.

I created a bug in the specification project, so maybe they will provide some guidance later on.

https://github.com/whatwg/url/issues/829

CPython versions tested on:

3.10

Operating systems tested on:

Linux, Windows

Start at the urllib.parse.urlsplit entry point and run the reproducer from the issue to confirm how an embedded tab changes the netloc. Read the linked WHATWG URL issue 829 for guidance on the specification conflict; done means tabs in the hostname are not silently turned into a different hostname.