Backports the fix for #200 to the 3.1-stable branch

git-svn-id: http://svn6.assembla.com/svn/pyfits/branches/3.1-stable@2094 ed100bfc-0583-0410-97f2-c26b58777a21
The expected results from this test need to be different in this branch due to the use of a different compression implementation

git-svn-id: http://svn6.assembla.com/svn/pyfits/branches/3.1-stable@2095 ed100bfc-0583-0410-97f2-c26b58777a21