Fix reverting builds stage ref migration on MySQL

db/migrate/20170526185602_add_stage_id_to_ci_builds.rb

@@ -13,8 +13,8 @@ class AddStageIdToCiBuilds < ActiveRecord::Migration
   end
 
   def down
-    remove_concurrent_index :ci_builds, :stage_id
     remove_foreign_key :ci_builds, column: :stage_id
+    remove_concurrent_index :ci_builds, :stage_id
 
     remove_column :ci_builds, :stage_id, :integer
   end

spec/migrations/migrate_build_stage_reference_spec.rb

@@ -16,7 +16,6 @@ describe MigrateBuildStageReference, :migration do
     #
     projects.create!(id: 123, name: 'gitlab1', path: 'gitlab1')
     projects.create!(id: 456, name: 'gitlab2', path: 'gitlab2')
-    projects.create!(id: 798, name: 'gitlab3', path: 'gitlab3')
 
     # Create CI/CD pipelines
     #