Redirect to files folder in a translation language not working

Hello

During the tests of the issue #2543606: Redirect to files folder on multilanguage website not working → , I discover a unexpected behaviour while defining a redirection.

When I try to access the URL "drupal-localhost/fr/sites/default/files/somefile.pdf", the interface display the "page not found" message + the invitation to create a redirection.
The language in the URL is "fr" which is not the default language.

When the form is displayed, the language code is not present in the "From" form field value; I have directly "sites/default/files/somefile.pdf" as value.
The expected behaviour would be to have "fr/sites/default/files/somefile.pdf" set in the "From" form field value

When I change the "From" value for "fr/sites/default/files/somefile.pdf" and save the redirection, the redirection is never applied and I receive again the the invitation to create a redirection.

I do not have this behaviour when the language code is the default language one; in my case, it was "en".

The patch proposed in #2543606: Redirect to files folder on multilanguage website not working → does not fix the problem.