rails caching bug

rails3.log

Site -> has_many :pages

> Rails.cache.fetch('test') { a = Array.new ; Site.all.each{|s| a.push(s) if s.pages.count > 1 } ; a }
  Site Load (0.7ms)  SELECT "sites".* FROM "sites" 
   (0.7ms)  SELECT COUNT(*) FROM "pages" WHERE "pages"."site_id" = 2
   (0.7ms)  SELECT COUNT(*) FROM "pages" WHERE "pages"."site_id" = 1
=> [#<Site id: 2, designer_id: 4, url: "http://tigris.id.au/", created_at: "2012-09-11 01:18:07", updated_at: "2012-09-11 01:18:07">, #<Site id: 1, designer_id: 1, url: "http://tigris.id.au/", created_at: "2012-09-02 16:39:54", updated_at: "2013-08-01 03:15:47">]

> Rails.cache.fetch('test') { a = Array.new ; Site.all.each{|s| a.push(s) if s.pages.count > 1 } ; a }
=> [#<Site id: 2, designer_id: 4, url: "http://tigris.id.au/", created_at: "2012-09-11 01:18:07", updated_at: "2012-09-11 01:18:07">, :@new_record, false]

rails4.log

League -> has_many :teams

> Rails.cache.fetch('test') { a = Array.new ; League.all.each{|l| a.push(l) if l.teams.count > 1 } ; a }
  League Load (1.1ms)  SELECT "leagues".* FROM "leagues"
   (0.7ms)  SELECT COUNT(*) FROM "teams" WHERE "teams"."league_id" = $1  [["league_id", 1]]
   (1.3ms)  SELECT COUNT(*) FROM "teams" WHERE "teams"."league_id" = $1  [["league_id", 2]]
=> [#<League id: 1, name: "Bamfy FFL", host: "ffl.tigris.id.au", team_limit: 10, rounds: 22>, #<League id: 2, name: "FantasyFL", host: "ffl2.tigris.id.au", team_limit: 8, rounds: 23>]

> Rails.cache.fetch('test') { a = Array.new ; League.all.each{|l| a.push(l) if l.teams.count > 1 } ; a }
=> [#<League id: 1, name: "Bamfy FFL", host: "ffl.tigris.id.au", team_limit: 10, rounds: 22>, #<League id: 2, name: "FantasyFL", host: "ffl2.tigris.id.au", team_limit: 8, rounds: 23>]