[Fedora-packaging] Bundling fun with html5-parser

Greetings. I maintain the calibre package (ebook library/reader) in Fedora. Recently they added a dependency on a html5-parser package (also maintained by the same upstream). Review is at: https://bugzilla.redhat.com/show_bug.cgi?id=1481046 html5-parser bundles a copy of https://github.com/Sigil-Ebook/sigil-gumbo which it then modifies and changes API on so it's no longer directly compatible with sigil-gumbo as far as I can see. sigul-gumbo is not in Fedora, but it in turn is a fork of gumbo-parser that is in Fedora. So, I cannot easily unbundle and package sigul-gumbo because its been further modified in the html5-parser fork. I guess then my last thing to do it just leave it bundled, but then do I need to have in a Provides line here? And I am asked to contact upstreams, I guess I should do this in reverse order? ie, ask html5-parser upstream if they can upstream their changes to sigul-gumbo and then ask sigul-gumbo if they want to ever merge back to gumbo-parser? (I am pretty sure I will get a big NO from both of them, but willing to try if required). Thoughts? kevin