builder: some small fixups + fix a bug where empty entrypoints would not override inheritance.

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)

builder/parser/parser.go

@@ -87,10 +87,11 @@ func parseLine(line string) (string, *Node, error) {
 
 	if sexp.Value != "" || sexp.Next != nil || sexp.Children != nil {
 		node.Next = sexp
-		node.Attributes = attrs
-		node.Original = line
 	}
 
+	node.Attributes = attrs
+	node.Original = line
+
 	return "", node, nil
 }