Merge branch 'master' into adequaterecord

* master: (122 commits)
  Rails.application should be set inside before_configuration hook
  remove check for present? from delete_all
  Remove useless begin..end
  Build the reverse_order on its proper method.
  Use connection-specific bytea escaping
  Ignore order when doing count.
  make enums distinct per class
  Remove unused `subclass_controller_with_flash_type_bar` var from flash test.
  fix CollectionProxy delete_all documentation
  Added OS X specific commands to installation guide [ci skip] Recommended using homebrew for installing MySQL and PostgreSQL
  Fix setup of adding _flash_types test.
  Use SVG version of travis build status badge [skip ci]
  W3C CSP document moved to gihub.io URL [ci skip]
  sprockets-rails was released
  Fix the test defining the models in the right place
  Add CHANGELOG entry for #11650 [ci skip]
  Declare the assets dependency
  Use sass-rails 4.0.3
  Make possible to use sprockets-rails 2.1
  add missing parentheses to validates_with documentation [skip ci]
  ...

1 files changed, 1 insertions, 1 deletions

diff --git a/activerecord/lib/active_record/core.rb b/activerecord/lib/active_record/core.rb
index 73ca468d80..eeb2f5430e 100644
--- a/activerecord/lib/active_record/core.rb
+++ b/activerecord/lib/active_record/core.rb
@@ -366,7 +366,7 @@ module ActiveRecord
     def ==(comparison_object)
       super ||
         comparison_object.instance_of?(self.class) &&
-        id &&
+        !id.nil? &&
         comparison_object.id == id
     end
     alias :eql? :==