rewrite or internal redirection cycle

[Roxis]

On Sunday 29 July 2007, Igor Sysoev wrote:
> This is because you have no location that matches request and
> request against server level rewrite rules: it does not match regex and
> goes to "return 403".

ok, i understand this:
location / {}
rewrite ^(/download/.*)/media/(.*)\..*$ $1/mp3/$2.mp3   last;
return  403;

but this:
location / {}
rewrite ^(/download/.*)/media/(.*)\..*$ $1/mp3/$2.mp3   break;
return  403;