Certain editor operations result in spurious "unpublished changes" and an empty diff

When opening an existing page, certain benign operations mark the editor as having unpublished changes. Of note, this will also cause the diff shown in the "View changes" menu item to be empty (no blue/green/red highlighted text)

Steps to reproduce

1. Edit an existing page
2. Focus the editor and do one of the things from the list below
3. Click "Close"

Expected:

• No unpublished changes lozenge on View Page

Actual:

• Unpublished changes lozenge on View Page

Known list of editor actions that trigger unpublished changes:

• Navigate cursor via keyboard arrow keys
• Page up/down, home
• Escape
• Select All
• Select text and press Copy (command+C)
• Open Insert menu, link dialog, or attachments dialog
• Preview
• Uncheck Notify Watchers

Note
The unpublished changes lozenge only shows to people that have entered the editor and made changes (spurious ones outlined in this ticket or real changes). Other historical contributors to the page or just page viewers will not see the lozenge. If the lozenge is really bothering you, proceed to the workaround below.

Workaround

• Under the ellipsis menu, click "Revert unpublished changes". Make sure you don't accidentally revert changes you do want to keep by clicking View Changes.