New answers tagged bug
The code in question was not generated by Stack Exchange. It was generated by a user. So, yes, quite often, the HTML (and all other code samples generated by users) will be malformed. However, in this case, note that <li> tags are not required to have closing tags. I agree that it is bad form to leave them off, though.
This is a bug. The timeline path seems to have several problems. More on these below. The earlier date query returns the result you expect, but look at it in the document explorer: Notice that the entry is a comment and that it has an Owning post. Now if we look at the whole timeline (filtering out some user cruft), we see: Just two revision entries ...
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