add a test for [ruby-core:14279].

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@14506 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

bootstraptest/test_knownbug.rb

@@ -3,3 +3,9 @@
 # So all tests will cause failure.
 #
 
+assert_normal_exit %{
+  def foo(&block)
+    yield if block
+  end
+  foo(&:bar)
+}, '[ruby-core:14279]'