Fix error when using `with_options` with lambda.

It was causing error when using `with_options` passing a lambda as its
last argument.

    class User < ActiveRecord::Base
      with_options dependent: :destroy do |assoc|
        assoc.has_many :profiles, -> { where(active: true) }
      end
    end

It was happening because the `option_merger` was taking the last
argument and checking if it was a Hash. This breaks the HasMany usage,
because its last argument can be a Hash or a Proc.

As the behavior described in this test:
https://github.com/rails/rails/blob/master/activesupport/test/option_merger_test.rb#L69
the method will only accept the lambda, this way it will keep the expected behavior. See 9eaa0a34

2 files changed, 6 insertions, 0 deletions

diff --git a/activerecord/test/models/college.rb b/activerecord/test/models/college.rb
index c7495d7deb..501af4a8dd 100644
--- a/activerecord/test/models/college.rb
+++ b/activerecord/test/models/college.rb
@@ -1,5 +1,10 @@
 require_dependency 'models/arunit2_model'
+require 'active_support/core_ext/object/with_options'
 
 class College < ARUnit2Model
   has_many :courses
+
+  with_options dependent: :destroy do |assoc|
+    assoc.has_many :students, -> { where(active: true) }
+  end
 end
diff --git a/activerecord/test/models/student.rb b/activerecord/test/models/student.rb
index f459f2a9a3..28a0b6c99b 100644
--- a/activerecord/test/models/student.rb
+++ b/activerecord/test/models/student.rb
@@ -1,3 +1,4 @@
 class Student < ActiveRecord::Base
   has_and_belongs_to_many :lessons
+  belongs_to :college
 end