IE: copy/paste problem in pre tag

[Jakub Ś]

Steps to reproduce :

1. Go the ckeditor.com/demo , clear the content
2. Go to Source view
3. Paste or Type the following code:

   <pre>
   
   This is test number one
   
   This is test number two
   
   This is another test
   
   </pre>
   

4. Go back to Design view
5. Select word ^number^ on the first line, press Ctrl+C (copy)
6. Select ^This^ on the second line , press Ctrl+V (overwriting 'This' with 'number')

Expected behavior:
The copied text should replace the contents ( 'This' should be replaced with 'number' )

Actual behavior:
Part of the original content is still visible.

Issue has been reproducible from CKEditor 3.1 in all versions of IE.