Steps to reproduce:

1. Open a page in the wikitext editor.

2. Switch to the visual editor. (It's not necessary to make any changes.)

3. Save the page. (Again, it's not necessary to make any changes; this is the equivalent of a null edit.)

4. Click the 'Edit' tab at the top of the page, to open the page in VisualEditor again.

Results:
You are greeted with a dialog box that says, "Switch to visual editing? You are switching to visual editing. Do you want to continue?"

Expected behavior:
Just open the page.