Scoped slug regeneration gives wrong slug

[PikachuEXE]

Rails 4.0.2, FriendlyId 5.0.2

Config:

config.use Module.new {
     def should_generate_new_friendly_id?
       slug.blank? || new_record?
     end
  }

Test Result:

b1=FactoryGirl.create(:building)
b1.slug
#=> "building-1"

b2=FactoryGirl.build(:building, neighbourhood: b1.neighbourhood, name: b1.name)
b2.send(:set_slug)
Building Exists (0.8ms)  SELECT 1 AS one FROM "buildings" WHERE "buildings"."neighbourhood_id" = 4 AND "buildings"."slug" = 'building-2' LIMIT 1
#=> "building-1--91415ad1-565b-43d6-9a4b-e8a23df3c041"

b2.send(:set_slug)
Building Exists (0.6ms)  SELECT 1 AS one FROM "buildings" WHERE "buildings"."neighbourhood_id" = 4 AND ("buildings"."id" <> NULL) AND "buildings"."slug" = 'building-2' LIMIT 1
#=> "building-1"

Model:

class Building
  include FriendlyId

  belongs_to :neighbourhood
  friendly_id :name_en, use: [:scoped], scope: :neighbourhood
end

[PikachuEXE]

Failed test added
PikachuEXE@a958dc9