nginx codeigniter rewrite: Controller name conflicts with directory

Question

I'm trying out nginx and porting my existing apache configuration to nginx. I have managed to reroute the codeigniter url's successfully, but I'm having a problem with one particular controller whose name coincides with a directory in site root.

I managed to make my codeigniter url's work as it did in Apache except that, I have a particular url say http://localhost/hello which coincides with a hello directory in site root. Apache had no problem with this. But nginx routes to this directory instead of the controller.

My reroute structure is as follows

http://host_name/incoming_url => http://host_name/index.php/incoming_url

All the codeigniter files are in site root.

My nginx configuration (relevant parts)

location / {
    # First attempt to serve request as file, then
    # as directory, then fall back to index.html

    index index.php index.html index.htm;

    try_files $uri $uri/ /index.php/$request_uri;

    #apache rewrite rule conversion

    if (!-e $request_filename){
        rewrite ^(.*)/?$ /index.php?/$1 last;
    }

    # Uncomment to enable naxsi on this location
    # include /etc/nginx/naxsi.rules
}

location ~ \.php.*$ {
    fastcgi_split_path_info ^(.+\.php)(/.+)$;
    # NOTE: You should have "cgi.fix_pathinfo = 0;" in php.ini

    # With php5-cgi alone:
    fastcgi_pass 127.0.0.1:9000;
    # With php5-fpm:
    #fastcgi_pass unix:/var/run/php5-fpm.sock;
    fastcgi_index index.php;
    include fastcgi_params;
}

EDIT:

my relevant apache htaccess configuration

    # Set the default file for indexes
DirectoryIndex index.php

<IfModule mod_rewrite.c>
    # mod_rewrite rules
    RewriteEngine on
    # If the file is NOT the index.php file
    RewriteCond %{REQUEST_FILENAME} !index.php
    # If the file/dir is NOT real go to index
    RewriteCond %{REQUEST_FILENAME} !-f
    #RewriteCond %{REQUEST_FILENAME} !-d
    RewriteRule ^(.*)$ index.php/$1 [QSA,L]

</IfModule>

I'm new to nginx and I need help in figuring out this directory conflict with the Controller name. I figured this configuration from various sources in the web, and any better way of writing my configuration is greatly appreciated.