support.rb in ruby-ole-1.2.12.2

- old
+ new

@@ -133,10 +133,10 @@
 	# streams a "tree" form of the recursively enumerable structure to +io+, or
 	# return a string form instead if +io+ is not specified.
 	#
 	# mostly a debugging aid. can specify a different block which will be called
 	# to provide the string form for each node.
-	def to_tree io='', &inspect
+	def to_tree io=''.dup, &inspect
 		inspect ||= :inspect.to_proc
 		io << "- #{inspect[self]}\n"
 		recurse = proc do |node, prefix|
 			child = nil
 			node.each_child do |next_child|