prevent coderay "warning: already initialized constant" on Ruby 1.8.7 (#13692)

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@11925 e93f8b46-1217-0410-a6f0-8f06a7374b81

Gemfile

@@ -3,7 +3,7 @@ source 'https://rubygems.org'
 gem "rails", "3.2.13"
 gem "jquery-rails", "~> 2.0.2"
 gem "i18n", "~> 0.6.0"
-gem "coderay", "~> 1.0.6"
+gem "coderay", "~> 1.0.9"
 gem "fastercsv", "~> 1.5.0", :platforms => [:mri_18, :mingw_18, :jruby]
 gem "builder", "3.0.0"