Pages with name ".." or "." can be created but not accessed

Steps to reproduce:

1. Create a page named "Test" with "Test content" as content.
2. Use the "Move / Rename" feature and rename the page to "..".
3. Try accessing the renamed page.

Expected result:

Either, renaming the page fails or the page can be accessed.

Actual result:

The renamed page cannot be accessed anymore.

Similar problems arise when the page is named ".".

The create page UI also doesn't warn when trying to create such a page, the user is simply redirected to the edit view of a page with the dots resolved (so, e.g., creating a "WebHome" space).