Relax test message expectation.

Author: ioquatix

test/io.rb

@@ -154,7 +154,7 @@
 			read_task = Async do
 				expect do
 					r.read(5)
-				end.to raise_exception(IOError, message: be =~ /stream closed/)
+				end.to raise_exception(IOError, message: be =~ /closed/)
 			end
 
 			close_thread = Thread.new do