title: Regex on security path in Symfony 2
body: <p>I'm trying to have a regex working for strings that exactly matches 2 or 3 long lowcase letters, in order to match /es/user ,  en/user ,  cat/user</p>
  
  <pre><code> - { path: ^/[a-z]+/user, role: [ROLE_USER]} 
  </code></pre>
  
  <p>is working but is not limiting to 2-3 letters length.</p>
  
  <pre><code>- { path: ^/[a-z]\{2,3}/user, role: [ROLE_USER]}
  </code></pre>
  
  <p>causes this error:</p>
  
  <pre><code>InvalidConfigurationException: Unrecognized options "3\}/user," under "security.access_control.0"
  </code></pre>