Merge branch 'fix-24-forks-seeder-cannot-find-project' into 'master'

Fix the seeder 24_forks.rb cannot find public project

See merge request gitlab-org/gitlab-ce!24031

db/fixtures/development/24_forks.rb

@@ -4,6 +4,12 @@ Sidekiq::Testing.inline! do
   Gitlab::Seeder.quiet do
     User.all.sample(10).each do |user|
       source_project = Project.public_only.sample
+
+      ##
+      # 04_project.rb might not have created a public project because
+      # we use randomized approach (e.g. `Array#sample`).
+      return unless source_project
+
       fork_project = Projects::ForkService.new(source_project, user, namespace: user.namespace).execute
 
       if fork_project.valid?