If you would look into the history of last revisions here, in the last revision by Peter Mortensen you'll see strange "changes" of lines into the absolutely same lines. Even twice. Is it a bug? Or I don't see something?
He added a line break between each of your lines so they changed from this:
Adding empty lines between list elements wraps the list elements in
is converted to
So from an HTML perspective, the contents of the list elements were indeed changed in a major way; hence this is very much by design. That's why the revisions list also offers a Markdown diff view; sometimes it's more helpful to see the changes to the source than to the rendered version.