BBCode: Unable to create Topic/Answer with 20000 symbols inside bb-code tags

Precondition:

User should be a registered user. User should be logged in at forum.

Topic creation.
Test scenario:

1. Go to any branch and click "New Topic" button.
2. Name the topic , press at any bb-code button
3. Add text from lorem ipsum.txt inside bb-code tags. (lorem ipsum.txt contains 20000 symbols)
4. Press "Save" button.

AR: warning size must be between 2 and 20000 showed.
ER: Topic created and accessible.

Answer creation.
Test scenario:

1. Go to any branch and choose any topic.
2. Focus at Answer screen.
3. Press at any bb-code button.
4. Add text from lorem ipsum.txt inside bb-code tags. (lorem ipsum.txt contains 20000 symbols)
5. Press "Answer" button.

AR: warning size must be between 2 and 20000 showed.
ER: Answer saved and accessible.

If user press "Preview" button, it shows the preview.
bug video - http://screencast.com/t/XXojN6RHt