This function does NOT do any diffing, it just checks the old and new files
    to see if either is binary, and provides an appropriate string noting the
    difference between the two files. If neither file is binary, an empty
    string is returned.

    This function should only be run AFTER it has been determined that the
    files differ.

def _binary_replace(old, new):
    '''
    This function does NOT do any diffing, it just checks the old and new files
    to see if either is binary, and provides an appropriate string noting the
    difference between the two files. If neither file is binary, an empty
    string is returned.

    This function should only be run AFTER it has been determined that the
    files differ.
    '''
    old_isbin = not __utils__['files.is_text'](old)
    new_isbin = not __utils__['files.is_text'](new)
    if any((old_isbin, new_isbin)):
        if all((old_isbin, new_isbin)):
            return 'Replace binary file'
        elif old_isbin:
            return 'Replace binary file with text file'
        elif new_isbin:
            return 'Replace text file with binary file'
    return ''