Post title is being appended to URL, resulting in invalid URL

[ats]

Mention URLs are being appended with a post's title as seen in the mention at this URL: https://prettygoodhat.com/note/letsencrypt-pair/; the correct mention URL is https://prettygoodhat.com/post/further-indieweb-adventures/; the URL linked in the mention is https://prettygoodhat.com/post/further-indieweb-adventures/Further%20adventures%20in%20IndieWeb -- the extra string is the title of the source post.

I apologize if this is a usage question and I've made a mistake in my formatting; but I'm honestly not sure how I could be mis-specifying the URL in this way. I don't see that url representation in my page source, anyway. Maybe this is a bug somewhere?

A portion of the JSON for that mention is below:

{"source":"https://prettygoodhat.com/post/further-indieweb-adventures/","target":"https://prettygoodhat.com/note/letsencrypt-pair/","data":{"url":"https://prettygoodhat.com/post/further-indieweb-adventures/Further%20adventures%20in%20IndieWeb","name":"Further adventures in IndieWeb","published":1520780017032,"summary":"[...]","author":{"name":"Alan S.","photo":"https://prettygoodhat.com/pics/u-photo.png","url":"https://prettygoodhat.com/"}}},