Nginx的配置文件server块里面有对PHP文件的识别和转发。

 location ~ [^/]\.php(/|$)
{
        # comment try_files $uri =404; to enable pathinfo
        try_files $uri =404;
        #fastcgi_pass  unix:/tmp/php-cgi.sock;
        fastcgi_pass 127.0.0.1:9000;
        fastcgi_index index.php;
        include fastcgi.conf;
        #include pathinfo.conf;
}

这段正则可以识别PHP结尾的文件。
但是为什么我访问`http://123.123.123.123/abc.abc.acb/index.php'
就出现了502错误？
如果我把上面的正则重复一遍就好了。

location ~ [^/]\.php(/|$)
        {
            try_files $uri =404;
            fastcgi_pass  unix:/tmp/php-cgi.sock;
            fastcgi_index index.php;
            include fastcgi.conf;
        }

 location ~ [^/]\.php(/|$)
{
        # comment try_files $uri =404; to enable pathinfo
        try_files $uri =404;
        #fastcgi_pass  unix:/tmp/php-cgi.sock;
        fastcgi_pass 127.0.0.1:9000;
        fastcgi_index index.php;
        include fastcgi.conf;
        #include pathinfo.conf;
}

这个样子，就能正常访问到PHP。这个是为什么？