Steps to reproduce:
1. Create a new document
2. Edit in WYSIWYG mode (CK)
2.1 (Optional) CTRL+R to hard-refresh the page and get rid of any caching you might have in the browser.
3. Switch to the "Source" tab(/button) of the CK editor
4. Enter some wiki syntax, e.g.
5. Switch to the Wiki editor (using the dropdown on the page's "Edit" button)
The content in the wiki editor should be the same as the content in the WYSIWYG editor's Source tab.
The wiki syntax gets escaped: