XSS filter name of document in blog

In a blog:

• Add a link to a document uploaded in the post entry (with spaces in the file name!)
• Save the post
• Check if the link works
• Reopen the post
• Check the link (spaces are replaced with %20, it's ok)
• Save the post a second time
• Check if the link works

Saving twice the post is very important as the XSS library will change the link. The changed link must interpreted again and saved correctly (changed but functionally correct).