fix for python exception getting the ID from an operator button:
  attempting to select 'Online Manual' or 'Python Reference' from the UI of a running operator would give an error popup.


git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@54835 954f8c5b-7b00-dc11-b283-0030488c597c