@Martha When I hit "edit", the message was right there in the source code. No idea why it wasn't displayed. (In fact, I am somewhat certain that I had seen it right after closing the question). Anyhow, I then hit "save" without touching anything else, and the message (re-)appeared, and the edit history
*almost* reflects that no changes were made, except for the edit summary that reads "added 5 characters in body". Really strange.