Yup, it basically trips the "oh no, file is gone" check, and it turns out that, besides purging the database, it also purges the actual file (which I assume is done as part of the process of deleting the associated sidecar/thumbnails), something which we had no really easy way to know/trigger before, as @davidfor just detailed the most common ways to trip that check, and they all involved the file being gone in the first place
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TL;DR: One could argue that borking the regex *was* in fact "asking for it"
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