title: SSH authentication fails on Jenkins Git poll (works on manual trigger)
body: <p>I have configured SSH authentication so Jenkins can checkout code from a GitHub repository.</p>
  
  <p>When I manually start a build, everything works fine. However, when I use a periodical poll, I get an authentication error.</p>
  
  <p>Started on Apr 21, 2014 11:02:14 PM
  Using strategy: Default
  [poll] Last Built Revision: Revision 2dd6b946d5274c0e802fd912e9c9aed9c1bafa7c (origin/desenv)
  using GIT_SSH to set credentials jenkins@glr.com.br
  FATAL: Command "git ls-remote -h git@github.com:felipe-gdr/game-of-life.git desenv" returned status code 128:
  stdout: 
  stderr: Permission denied (publickey).
  fatal: Could not read from remote repository.</p>
  
  <p>Please make sure you have the correct access rights
  and the repository exists.</p>