'Get the published branch and find when it was published if it was. Cache the results in the xblock'

def compute_published_info_internal(self, xblock):

    published_block = self._get_head(xblock, ModuleStoreEnum.BranchName.published)
    if (published_block is not None):
        xblock._published_by = published_block.edit_info.edited_by
        xblock._published_on = published_block.edit_info.edited_on
