add a test for concatinating euc-jp and ascii-8bit string.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@14140 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

bootstraptest/test_knownbug.rb

@@ -47,3 +47,12 @@ assert_equal 'ok', %q{
     :ng
   end
 }, '[ruby-dev:32452]'
+
+assert_equal 'ok', %q{
+  begin
+    "\xa1\xa1".force_encoding("euc-jp") + "\xa1".force_encoding("ascii-8bit")
+    :ng
+  rescue ArgumentError
+    :ok
+  end
+}