This doesn't happen all the time, but I managed to reproduce in two cases:

• Edit a wiki page using the real-time WYSIWYG editor, select all content, delete, click Save & View
• Edit a wiki page using the real-time WYSIWYG editor, insert an info box macro, make sure the caret is inside the info box (editable in-place), click Save & View

In both cases you get the leave confirmation modal, which is not expected because the content was just saved.