def modified_md5_decider(dependency, target, prev_ni):
    """SCons MD5 Decider function that checks if targets have changed"""
    # Use default checking for changes in the source file
    source_changed = dependency.changed_content(target, prev_ni)
    if source_changed:
        return source_changed
    else:
        target_changed = False
        # If target node does not implement get_csig(), do not try to determine
        # whether to rebuild. (csig = content signature)
        try:
            target_info = target.get_stored_info()
            if target_info.ninfo.csig != target.get_csig():
                target_changed = True
        except AttributeError:
            pass

        return target_changed

# Set the SCons Decider function
Decider(modified_md5_decider)