Writable books permanently save blank visited pages (minus 2)

The bug

If you scroll to a blank page of a book and quill, the book will permanently be modified to contain that many pages, even if you don't write anything.

How to reproduce

1. Get a book and quill from the creative inventory
2. Open it and press "next" a bunch of times, to page 20 or so
3. Close the book and reopen it
   →   Total number of pages is 20, even though you didn't type anything

Update

In 1.12.0.11, the last two blank pages are deleted.