Remove unique index not added in a migration from schema

db/schema.rb

@@ -451,7 +451,6 @@ ActiveRecord::Schema.define(version: 20180125111139) do
   end
   add_index "ci_stages", ["pipeline_id", "name"], name: "index_ci_stages_on_pipeline_id_and_name", unique: true, using: :btree
-  add_index "ci_stages", ["pipeline_id", "name"], name: "index_ci_stages_on_pipeline_id_and_name_unique", unique: true, using: :btree
   add_index "ci_stages", ["pipeline_id"], name: "index_ci_stages_on_pipeline_id", using: :btree
   add_index "ci_stages", ["project_id"], name: "index_ci_stages_on_project_id", using: :btree