title: htaccess rewrite not working for multiple files in main directory
body: <p>The title does not fully describe the issue, but I have rewrite rules setup to go to three different files which exist in the main directory: api.php, admin.php, and index.php</p>
  
  <p><strong>Here is my .htaccess</strong></p>
  
  <pre><code>RewriteEngine on
  RewriteCond $1 ^(api)
  RewriteRule ^(.*)$ /api.php/$1 [L]
  
  RewriteCond $1 ^(admin)
  RewriteRule ^(.*)$ /admin.php/$1 [L]
  
  RewriteCond $1 !^(index\.php|admin\.php|api\.php|admin|api|_|robots\.txt)
  RewriteRule ^(.*)$ /index.php/$1 [L]
  </code></pre>
  
  <p>For /admin and /api I get a 500 Internal Server Error.  I am not sure why that happens, yet if I put those php files within a folder like /_ and edit the .htaccess to match it then it rewrites without an error. Am I limited on the number of main directory file redirects I can do? Or did I am I missing something?</p>
  
  <p><strong>My main goal is:</strong></p>
  
  <p>Redirect all /api requests to /api.php/whatever/is/after/here</p>
  
  <p>Redirect all /admin requests to /admin.php/whatever/is/after/here</p>
  
  <p>Redirect all other requests apart from the exceptions to /index.php/whatever/is/here</p>