This came up in Windows testing, specifically with the test 'test_update_resized_header2'.  The problem is that the buffer for non-mmap'd arrays was being unncessarily replaced on writing, causing corruption of the original array.
This came up in Windows testing, specifically with the test 'test_update_resized_header2'.  The problem is that the buffer for non-mmap'd arrays was being unncessarily replaced on writing, causing corruption of the original array.

git-svn-id: 5305e2c1a78737cf7dd5f8f44e9bbbd00348fde7@1648 ed100bfc-0583-0410-97f2-c26b58777a21

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