It looks like that "feature" is guilty, and I falsely blamed translators.

On 04.04.2013 21:33, Ameen Ross wrote:
Are you using the redirect module? I know only of that module that adds redirects for title updates, so as to prevent breaking the old URL. If that causes issues, like a circular redirect, there are already numerous issue reports and AFAICT a fix is around the corner.

Aleksey Bragin <aleksey@reactos.org> wrote:
It turns out, that Drupal automatically (!??!!?) adds this redirect when 
title of the translated page is changed. This needs to be tested and if 
so, complained to the Drupal [module] developers, because this "feature" 
is very bad.

Best regards,
Aleksey Bragin

On 04.04.2013 13:30, Aleksey Bragin wrote:
Dear translators, please DO NOT SET the url redirection in your translated pages (unless you was told so by Z98 or me). I repeat, DO NOT SET it at all. DO NOT try to fix the url by doing so, don't try to think you're smarter and can work around the different url problem by setting the redirects. Drupal 7 is not smarter alas, and doesn't detect circular references in all cases. Thanks for understanding, Aleksey Bragin