xref in nav file breaks if nav path matches target page path
If the root-relative path of the nav file matches the root-relative path of the target page, then the xref resolves to #
. This happens because Asciidoctor thinks they are the same file.
This issue can be resolved by prefixing the docname attribute with 'nav$' (the family prefix) when the family is nav. This will not otherwise affect how Antora or Asciidoctor works, other than it will allow Asciidoctor to distinguish between the two files (it won't think they are the same file).