Searches lead to 303 error when accented character in tag or category

Hi!

I had an unexpected behaviour while testing searching and filtering tools. When i search for text with accented characters, it works perfectly. But when i add filters to the search with tags or categories with accented characters, i am redirected to the site home page with a 303 (see other).

I provided pictures to show it with some details. You can see the category exists in the first picture (the category itself actually behaves correctly, it shows without errors in category lists and such). You can also see in the details (last picture) that the character is sent and URL encoded correctly.

Can you tell me if it comes from some configuration of mine, or a bug?
(note: i am working on a beta site which is not the one provided for support, if you need it, just ask)

Thanks.