Non-functional reply links appear for some messages wrapped in <div>.
Example: https://en.wikipedia.beta.wmflabs.org/wiki/User_talk:Yatu
Note how when you click "reply", the placeholder text is "Reply to Yatu" instead of "Reply to Test". Something goes very wrong, and the wrong username comes from the "edit source" link on the sub-heading rather than from the actual signature. (And then the reply can't be saved, because we can't find any comment by "Yatu" on the page.)
There should be no reply link at all, because the timestamp is on a different line of text than the user page links.
Originally reported here: https://www.mediawiki.org/wiki/Topic:Vt5zo2ibvrkzfnxj