Adds the Rubocop ReturnNil cop

This style change enforces `return if ...` instead of
`return nil if ...` to save maintainers a few minor review points

app/models/project.rb

@@ -1230,7 +1230,7 @@ class Project < ActiveRecord::Base
   end
   def fork_source
-    return nil unless forked?
+    return unless forked?
     forked_from_project || fork_network&.root_project
   end
@@ -1679,7 +1679,7 @@ class Project < ActiveRecord::Base
   end
   def export_path
-    return nil unless namespace.present? || hashed_storage?(:repository)
+    return unless namespace.present? || hashed_storage?(:repository)
     import_export_shared.archive_path
   end

app/models/project_services/campfire_service.rb

@@ -57,7 +57,7 @@ class CampfireService < Service
   # https://github.com/basecamp/campfire-api/blob/master/sections/messages.md#create-message
   def speak(room_name, message, auth)
     room = rooms(auth).find { |r| r["name"] == room_name }
-    return nil unless room
+    return unless room
     path = "/room/#{room["id"]}/speak.json"
     body = {

app/models/project_services/irker_service.rb

@@ -112,7 +112,7 @@ class IrkerService < Service
   end
   def consider_uri(uri)
-    return nil if uri.scheme.nil?
+    return if uri.scheme.nil?
     # Authorize both irc://domain.com/#chan and irc://domain.com/chan
     if uri.is_a?(URI) && uri.scheme[/^ircs?\z/] && !uri.path.nil?

app/models/repository.rb

@@ -79,7 +79,7 @@ class Repository
   end
   def raw_repository
-    return nil unless full_path
+    return unless full_path
     @raw_repository ||= initialize_raw_repository
   end
@@ -103,7 +103,7 @@ class Repository
   end
   def commit(ref = nil)
-    return nil unless exists?
+    return unless exists?
     return ref if ref.is_a?(::Commit)
     find_commit(ref || root_ref)

app/models/ssh_host_key.rb

@@ -27,7 +27,7 @@ class SshHostKey
   def self.find_by(opts = {})
     opts = HashWithIndifferentAccess.new(opts)
-    return nil unless opts.key?(:id)
+    return unless opts.key?(:id)
     project_id, url = opts[:id].split(':', 2)
     project = Project.find_by(id: project_id)

app/models/user.rb

@@ -470,7 +470,7 @@ class User < ApplicationRecord
     end
     def by_login(login)
-      return nil unless login
+      return unless login
       if login.include?('@'.freeze)
         unscoped.iwhere(email: login).take

app/models/wiki_page.rb

@@ -132,7 +132,7 @@ class WikiPage
   # The GitLab Commit instance for this page.
   def version
-    return nil unless persisted?
+    return unless persisted?
     @version ||= @page.version
   end

app/serializers/concerns/user_status_tooltip.rb

@@ -11,7 +11,7 @@ module UserStatusTooltip
     expose :user_status_if_loaded, as: :status_tooltip_html
     def user_status_if_loaded
-      return nil unless object.association(:status).loaded?
+      return unless object.association(:status).loaded?
       user_status(object)
     end

app/services/application_settings/update_service.rb

@@ -38,7 +38,7 @@ module ApplicationSettings
     def performance_bar_allowed_group_id
       performance_bar_enabled = !params.key?(:performance_bar_enabled) || params.delete(:performance_bar_enabled)
       group_full_path = params.delete(:performance_bar_allowed_group_path)
-      return nil unless Gitlab::Utils.to_boolean(performance_bar_enabled)
+      return unless Gitlab::Utils.to_boolean(performance_bar_enabled)
       Group.find_by_full_path(group_full_path)&.id if group_full_path.present?
     end

app/services/boards/visits/latest_service.rb

@@ -4,7 +4,7 @@ module Boards
   module Visits
     class LatestService < Boards::BaseService
       def execute
-        return nil unless current_user
+        return unless current_user
         recent_visit_model.latest(current_user, parent, count: params[:count])
       end

app/services/groups/nested_create_service.rb

@@ -12,7 +12,7 @@ module Groups
     end
     def execute
-      return nil unless group_path
+      return unless group_path
       if namespace = namespace_or_group(group_path)
         return namespace

app/services/projects/download_service.rb

@@ -11,7 +11,7 @@ module Projects
     end
     def execute
-      return nil unless valid_url?(@url)
+      return unless valid_url?(@url)
       uploader = FileUploader.new(@project)
       uploader.download!(@url)

app/services/push_event_payload_service.rb

@@ -46,7 +46,7 @@ class PushEventPayloadService
   def commit_title
     commit = @push_data.fetch(:commits).last
-    return nil unless commit && commit[:message]
+    return unless commit && commit[:message]
     raw_msg = commit[:message]

app/services/upload_service.rb

@@ -6,7 +6,7 @@ class UploadService
   end
   def execute
-    return nil unless @file && @file.size <= max_attachment_size
+    return unless @file && @file.size <= max_attachment_size
     uploader = @uploader_class.new(@model, nil, @uploader_context)
     uploader.store!(@file)

lib/api/helpers/pagination.rb

@@ -149,7 +149,7 @@ module API
         def conditions(pagination)
           fields = pagination.fields
-          return nil if fields.empty?
+          return if fields.empty?
           placeholder = fields.map { '?' }

lib/bitbucket_server/collection.rb

@@ -25,13 +25,13 @@ module BitbucketServer
     end
     def prev_page
-      return nil unless current_page > 1
+      return unless current_page > 1
       current_page - 1
     end
     def next_page
-      return nil unless has_next_page?
+      return unless has_next_page?
       current_page + 1
     end

lib/declarative_policy/rule.rb

@@ -84,7 +84,7 @@ module DeclarativePolicy
       # returns nil unless it's already cached
       def cached_pass?(context)
         condition = context.condition(@name)
-        return nil unless condition.cached?
+        return unless condition.cached?
         condition.pass?
       end
@@ -124,7 +124,7 @@ module DeclarativePolicy
       def cached_pass?(context)
         condition = delegated_context(context).condition(@name)
-        return nil unless condition.cached?
+        return unless condition.cached?
         condition.pass?
       rescue MissingDelegate
@@ -161,7 +161,7 @@ module DeclarativePolicy
       def cached_pass?(context)
         runner = context.runner(@ability)
-        return nil unless runner.cached?
+        return unless runner.cached?
         runner.pass?
       end

lib/gitlab/auth/ldap/config.rb

@@ -195,7 +195,7 @@ module Gitlab
         def encryption_options
           method = translate_method
-          return nil unless method
+          return unless method
           {
             method: method,
@@ -211,7 +211,7 @@ module Gitlab
           return @tls_options if defined?(@tls_options)
           method = translate_method
-          return nil unless method
+          return unless method
           opts = if options['verify_certificates'] && method != 'plain'
                    # Dup so we don't accidentally overwrite the constant

lib/gitlab/auth/ldap/person.rb

@@ -112,7 +112,7 @@ module Gitlab
           attributes = Array(config.attributes[attribute.to_s])
           selected_attr = attributes.find { |attr| entry.respond_to?(attr) }
-          return nil unless selected_attr
+          return unless selected_attr
           entry.public_send(selected_attr) # rubocop:disable GitlabSecurity/PublicSend
         end

lib/gitlab/auth/saml/auth_hash.rb

@@ -10,11 +10,11 @@ module Gitlab
         def authn_context
           response_object = auth_hash.extra[:response_object]
-          return nil if response_object.blank?
+          return if response_object.blank?
           document = response_object.decrypted_document
           document ||= response_object.document
-          return nil if document.blank?
+          return if document.blank?
           extract_authn_context(document)
         end