'If a block was inherited into another structure using copy_from_template,
this will return the original block usage locator and version from
which the copy was inherited.
Returns usage_key, version if the data is available, otherwise returns (None, None)'

def get_block_original_usage(self, usage_key):

    blocks = self._lookup_course(usage_key.course_key).structure['blocks']
    block = blocks.get(BlockKey.from_usage_key(usage_key))
    if (block and (block.edit_info.original_usage is not None)):
        usage_key = BlockUsageLocator.from_string(block.edit_info.original_usage)
        return (usage_key, block.edit_info.original_usage_version)
    return (None, None)
