Sadly this one doesn't work; the link comes out missing an underscore after the octathorpe:

http://0.0.0.0:8000/packaging-guidelines/Versioning/#handling_non_sorting_versions_with_tilde_dot_and_caret

instead of

http://0.0.0.0:8000/packaging-guidelines/Versioning/#_handling_non_sorting_versions_with_tilde_dot_and_caret

I don't know enough asciidoc to know what the real solution would be, but I'll try to find out.

Edit: I got the links backwards initially. The good one has the underscore, the bad one doesn't.

Just add the underscore to the xref:

xref:_handling_non_sorting_versions_with_tilde_dot_and_caret[foo]

The undercore is always there when a section does not have a named anchor
and the default one generated from section title is used.

Alternatively, add a named anchor and refer to that:

[[tilde_dot_caret]]
=== Handling non-sorting versions with tilde, dot, and caret
...
xref:tilde_dot_caret[foo]

@oturpe thx for suggestion. I have pushed update with the underscore. Hope it helps.