Backport project.merge_requests_ff_only_enabled field from EE

db/migrate/20150827121444_add_fast_forward_option_to_project.rb

+# rubocop:disable all
+class AddFastForwardOptionToProject < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  # Set this constant to true if this migration requires downtime.
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  def add
+    add_column_with_default(:projects, :merge_requests_ff_only_enabled, :boolean, default: false)
+  end
+
+  def down
+    remove_column(:projects, :merge_requests_ff_only_enabled)
+  end
+end

db/schema.rb

@@ -1216,6 +1216,7 @@ ActiveRecord::Schema.define(version: 20170918223303) do
     t.datetime "last_repository_updated_at"
     t.integer "storage_version", limit: 2
     t.boolean "resolve_outdated_diff_discussions"
+    t.boolean "merge_requests_ff_only_enabled", default: false
   end
 
   add_index "projects", ["ci_id"], name: "index_projects_on_ci_id", using: :btree