Fixed that previews are broken by r10957 (#12642).

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@11133 e93f8b46-1217-0410-a6f0-8f06a7374b81
Removed debug messages.

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@11134 e93f8b46-1217-0410-a6f0-8f06a7374b81