title: Tomcat hot deployment, JDBC driver failed to unregister
body: <p>I have the exception after updating a file and hot deployment it to <code>Tomcat</code> server.<br>
  Does anybody know what is wrong?</p>
  
  <pre><code>SEVERE: The web application [/app] registered the JDBC driver [org.postgresql.Driver]  
  but failed to unregister it when the web application was stopped.
  To prevent a memory leak, the JDBC Driver has been forcibly unregistered.
  </code></pre>
  
  <p>Env.</p>
  
  <pre><code>     - Tomcat 6 or 7 (the same error)
       - Eclipse Helios
       - JDK 1.7.0_55 with "Default VM parameters":
         -Xms256M -Xmx512M -XX:PermSize=256M -XX:MaxPermSize=512M
  </code></pre>