I read documentation for further details and that's what i found:

if: "Checks the truth of a condition. If the condition evaluates to true, then
the code indicated in the curly braces is carried out and the request is
processed in accordance with the configuration within the following block."

location: "While nested locations are allowed by the configuration file parser,
their use is discouraged and may produce unexpected results."

http://wiki.nginx.org/NginxHttpRewriteModule#if In examples we can clearly see
that it is used with proxy_pass, which is similar fastcgi_pass.

I'll add the break, but as I said try passing JPG files to fastcgi - this seams
to be a problem in my case. Because in some cases fastcgi_pass was the last if()
in location and still it led to the crash.

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,3374,3540#msg-3540