Creating a page by uploading an attachment via quick actions creates the page with the root locale

Steps to reproduce:

1. Edit the wiki's configuration to enable multilingual. No need to enable any extra languages.
2. Create a new page (open the editor, don't save it)
3. Type [ and upload a file
4. Save the page

Expected result:

The page has been created with the English locale and there is no translation of it.

Actual result:

The page has been created with "root" locale (and empty content) and when saving the page, a translation into English has been created. When switching to the root locale, the content of the page is empty and in the page information there is no way to select the "English" version again.

Note that this can also be reproduced without enabling multilingual. In this case, there is only one version of the page but it still has the root locale instead of the wiki's locale.