title: can't upgrade jenkins for java version error
body: <p>I have Jenkins running on my Ubuntu 14.04, and i am trying to do upgrade for jenkins using normal <code>apt-get install jenkins</code>, but when i try to do it, i keep getting the error:</p>
  
  <pre><code>Setting up jenkins (2.73) ...
  Found an incorrect Java version
  Java version found:
  java version "1.7.0_131"
  OpenJDK Runtime Environment (IcedTea 2.6.9) (7u131-2.6.9-0ubuntu0.14.04.2)
  OpenJDK 64-Bit Server VM (build 24.131-b00, mixed mode)
  
  Aborting
  invoke-rc.d: initscript jenkins, action "start" failed.
  dpkg: error processing package jenkins (--configure):
   subprocess installed post-installation script returned error exit status 1
  Errors were encountered while processing:
   jenkins
  E: Sub-process /usr/bin/dpkg returned an error code (1)
  </code></pre>
  
  <p>Nothing shown in the jenkins logs, even when restarting jenkins i get the same jave wrong version error,</p>
  
  <p>Any help please?</p>