Yeah, it’s weird. I did try running the same command two three more times, and each time it remapped 333 more posts… 
In the log it’s showing a bunch of supposed replacements, except that when I reload the page and inspect the actual post it remains unchanged:
This seemed to me like a caching issue, so I did a redis-cli flushall and hard-reloaded Discourse, but still no change in the posts that were reported as edited in the log.
And also in the error log a bunch of messages like this:
