spec: don't override base_transactions in onceler noop

Change-Id: I195885e7f56bdfc8c10f454f6660261854a2277d
Reviewed-on: https://gerrit.instructure.com/37970
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Cody Cutrer <cody@instructure.com>
Product-Review: James Williams  <jamesw@instructure.com>
QA-Review: James Williams  <jamesw@instructure.com>

spec/sharding_spec_helper.rb

@@ -22,13 +22,12 @@ require File.expand_path(File.dirname(__FILE__) + '/support/onceler/sharding')
 SHARDING_ENABLED = defined?(ShardRSpecHelper)
 
 unless SHARDING_ENABLED
-  require File.expand_path(File.dirname(__FILE__) + '/support/onceler/noop')
-
   module ShardRSpecHelper
     def self.included(klass)
       klass.before do
         pending "needs a sharding implementation"
       end
+      require File.expand_path(File.dirname(__FILE__) + '/support/onceler/noop') unless defined?(Onceler::Noop)
       klass.send(:include, Onceler::Noop)
     end
   end

spec/support/onceler/noop.rb

@@ -1,8 +1,10 @@
 # dummy methods for CANVAS_RAILS2
 module Onceler
+  unless self.method_defined?(:base_transactions)
     def self.base_transactions
       1
     end
+  end
 
   module Noop
     def self.included(mod)