Fixed unsafe call to #casecmp (#20369, #21000).

git-svn-id: http://svn.redmine.org/redmine/trunk@14676 e93f8b46-1217-0410-a6f0-8f06a7374b81

app/helpers/application_helper.rb

@@ -609,7 +609,7 @@ module ApplicationHelper
       parsed << text
       if tag
         if closing
-          if tags.last.casecmp(tag) == 0
+          if tags.last && tags.last.casecmp(tag) == 0
             tags.pop
           end
         else

test/unit/helpers/application_helper_test.rb

@@ -994,6 +994,12 @@ EXPECTED
     assert_equal expected.gsub(%r{[\r\n\t]}, ''), textilizable(raw).gsub(%r{[\r\n\t]}, '')
   end
 
+  def test_unbalanced_closing_pre_tag_should_not_error
+    assert_nothing_raised do
+      textilizable("unbalanced</pre>")
+    end
+  end
+
   def test_syntax_highlight
     raw = <<-RAW
 <pre><code class="ruby">