Fix a small python 3 bug that resulted from an earlier interface change that wasn't carried over in one of the Python 3 monkey patches.
Fix a small python 3 bug that resulted from an earlier interface change that wasn't carried over in one of the Python 3 monkey patches.

git-svn-id: 5305e2c1a78737cf7dd5f8f44e9bbbd00348fde7@1235 ed100bfc-0583-0410-97f2-c26b58777a21

spacetelescope/PyFITS,embray/PyFITS,embray/PyFITS,embray/PyFITS,embray/PyFITS,spacetelescope/PyFITS