MTChangelog4 - solving the rebuild error, atomically

So I imported all the entries from the Marginalia sideblog into the main ortholog blog. I set up differential formatting based on MTCompare to replicate the effect I was getting from MTIfLocalBlog and MTIfNotLocalBlog switching. Seemed to work but--nuts!--the rebuild problem remained.

Control for variables: I tried rebuilding the indexes one by one. Aha--the failure comes from the Atom Index template. Unchecking the "Rebuild this template automatically" box prevents the error.

Next step is diagnosis. First hunch: perhaps my ISP's Perl version isn't up to the task of something the Atom Index is asking for…? I suspect the culprit is the <$MTEntryModifiedDate utc="1" format="%Y-%m-%dT%H:%M:%SZ"$> tag, since it this the only one I haven't seen in other templates.

Hm. Symptom addressed. Disease not cured.