Empty Select language list is displayed when editing.

Steps:

1. Create a user which can only edit in English (example attached).
2. As admin publish an item in (only) French.
3. Log in as user from step 1.
4. Select item from step 2.
5. Click Edit.

Actual result: Edit button is enabled, empty Select language list appears.
Expected result: Edit button is disabled.

Remarks: Does not affect v2.5.7, only stable branch 2.5. Seems it's caused by the changes from EZP-30997.