Unable to edit the original document if it has default language blank and en (configured default translation) translation exists

Steps to reproduce:

1. Set the wiki multilingual, with default language en and available languages en,fr
2. Create a new page and set its default language to blank (advanced user, wiki edit mode).
   1. Set the content to Original content.
3. Create an en translation of that document.
   1. Set the content to English content.
4. Try to go back to the original document in edit mode (press the "default" link in the existing translations section).
5. You will always be editing the en translation and are not able to go back to the original document.

Workaround:
Go to the english translation and hit delete page, in order to delete the english translation. This will leave the original document editable.