Take care of "Node-action: delete" as soon as possible, so we can stop
worrying about that case in the rest of the function.
Functional change: catch deletion nodes with features that would not
apply to them (text, properties, or origin data) and error out for
those cases.
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>