runner.rb: include event name

* test/runner.rb (after_teardown): include active trace event name
  in the failure message.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46431 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/runner.rb

@@ -25,7 +25,7 @@ module Test::Unit
 
       # detect zombie traces.
       TracePoint.stat.each{|key, (activated, deleted)|
-        assert_equal(0, activated, 'The number of active trace events should be zero.')
+        assert_equal(0, activated, "The number of active trace events (#{key}) should be zero.")
         # puts "TracePoint - deleted: #{deleted}" if deleted > 0
       }
     end