add a test for [ruby-core:14385] reported by Frederick Cheung.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@14615 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

bootstraptest/test_knownbug.rb

@@ -2,3 +2,12 @@
 # This test file concludes tests which point out known bugs.
 # So all tests will cause failure.
 #
+
+assert_normal_exit %q{
+  counter = 2
+  while true
+    counter -= 1
+    next if counter != 0
+    break
+  end
+}, '[ruby-core:14385]'