Merge pull request #12065 from SamSaffron/result_optimisation

Perf: micro optimised Result column hash_row creation
Merge branch '4-0-stable' of github.com:rails/rails into 4-0-stable

* '4-0-stable' of github.com:rails/rails:
  Merge pull request #12135 from dylanahsmith/avoid_empty_transaction
  Merge pull request #12185 from SamSaffron/join_dep
  Merge pull request #12194 from thedarkone/readonly-merger-fix
  Merge pull request #12148 from gzohari/callback-typo
  Merge pull request #12143 from rajcybage/fixing_typos
  Merge pull request #12139 from vipulnsward/typos_av
  Merge pull request #12130 from egilburg/patch-1