scm: fix error on revision page for empty revision (#7307).

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@4703 e93f8b46-1217-0410-a6f0-8f06a7374b81

app/controllers/repositories_controller.rb

@@ -139,6 +139,7 @@ class RepositoriesController < ApplicationController
   end
   
   def revision
+    raise ChangesetNotFound if @rev.nil? || @rev.empty?
     @changeset = @repository.find_changeset_by_name(@rev)
     raise ChangesetNotFound unless @changeset