Sharing page with username or email address which consists of Chinese characters will returned "No matching user or email found"

Steps to reproduce:

1. Create a Mail Server (This will make Share button available)
2. Create a Chinese username e.g. 招呼你
3. Rebuild search index
4. Typed in username 招呼你 in the Share page field
5. This will resulted in "No matching user or email found"

PS: The same result will be returned even the indexing language is set to Chinese. In Confluence 4.1, searching up Chinese username will work if the indexing language is set to Chinese.