backout r12540 : remove unneeded Relation#all from News#latest

git-svn-id: http://svn.redmine.org/redmine/trunk@12566 e93f8b46-1217-0410-a6f0-8f06a7374b81
backout r12562 : remove unneeded Relation#all from Repository::Mercurial#latest_changesets

git-svn-id: http://svn.redmine.org/redmine/trunk@12567 e93f8b46-1217-0410-a6f0-8f06a7374b81