Merged r11925 from trunk to 2.3-stable (#13692)

prevent coderay "warning: already initialized constant" on Ruby 1.8.7.

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/branches/2.3-stable@11929 e93f8b46-1217-0410-a6f0-8f06a7374b81