It no longer needs a block, feedback:

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/6342#note_15434727

app/models/project_services/pipelines_email_service.rb

 class PipelinesEmailService < Service
   prop_accessor :recipients
   boolean_accessor :notify_only_broken_pipelines
-  validates :recipients,
-    presence: true,
-    if: ->(s) { s.activated? }
+  validates :recipients, presence: true, if: :activated?
 
   def initialize_properties
     self.properties ||= { notify_only_broken_pipelines: true }