babel 3.42 (and later?): "nohyphenation" and languages that use "zerohyph.tex" aren't recognized

Babel 3.42 seems to show some inconsistent behaviour with the dummy language nohyphenation and some other languages such as farsi which can be chosen within macros such as foreignlanguage to avoid hyphenation in a short piece of text.

It gives this warning:

Package babel Warning: Unknown language `nohyphenation’. Either you have misspelled its name, it has not been installed, or you requested it in a previous run. Fix its name, install it or just rerun the file, respectively. […]

The manual says

…provided that in language.dat the ‘language’ nohyphenation is defined by loading zerohyph.tex"

and this is indeed my case: nohyphenation is defined in language.dat, and its corresponding file, zerohyph.tex, is also in the TeXLive path and reported by kpsewhich.

If I replace nohyphenation with some other language, say dutch, no warnings appear. The only difference I’ve found between the two languages is that zerohyph.tex is in the directory generichyphen whereas the one for dutch is in generichyph-utf8loadhyph. (Neither the package hyphen or hyph-utf8 are directly called in the preamble.)

If I replace nohyphenation with something that’s undefined in language.dat, say doesntexist, then I get an error rather than a warning:

Package babel Error: You haven’t defined the language doesntexist yet.

The same problem exists for farsi and all languages in language.dat that rely on zerohyph.tex.

Must I give some extra option to the babel package so that nohyphenation is recognized?

I’m using TeXLive 2020 on Windows 10. Babel is called with just the main=british option.

Here is a minimal working example:

documentclass{article}

usepackage[main=british]{babel}

begin{document}

Some text.

foreignlanguage{dutch}{some text not in Dutch.}

foreignlanguage{nohyphenation}{some text not to be hyphenated.}

foreignlanguage{farsi}{some text not in Farsi.}

end{document}

Thank you!

documentclass{article}

usepackage[british]{babel}

begin{document}

Some text.

foreignlanguage{dutch}{some text not in Dutch.}

foreignlanguage{nohyphenation}{some text not to be hyphenated.}

begin{hyphenrules}{nohyphenation}some text not to be hyphenated.end{hyphenrules}

end{document}

Package babel Warning: You haven't loaded the language dutch yet
(babel)                I'll proceed, but expect unexpected results.
(babel)                Reported on input line 9.


Package babel Warning: You haven't loaded the language nohyphenation yet
(babel)                I'll proceed, but expect unexpected results.
(babel)                Reported on input line 11.

Package babel Warning: Unknown language `nohyphenation'. Either you have
(babel)                misspelled its name, it has not been installed,
(babel)                or you requested it in a previous run. Fix its name,
(babel)                install it or just rerun the file, respectively. In
(babel)                some cases, you may need to remove the aux file.
(babel)                I'll proceed, but expect wrong results.
(babel)                Reported on input line 11.