The doc does not say any such thing. A tag object does not have 'parent'
nor 'tree' header fields.
Neither a commit have 'object' nor 'type' header fields and you cannot ask
for them when showing a commit object.
--
To unsubscribe from this list: send the line "unsubscribe git" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html