Merge branch 'sh-fix-ee-load-balancing' into 'master'

Fix EE load balancing crashing on Rails 5

Closes #8692

See merge request gitlab-org/gitlab-ee!8687

ee/lib/gitlab/database/load_balancing/connection_proxy.rb

@@ -30,7 +30,7 @@ module Gitlab
           read_using_load_balancer(:select, args)
         end
 
-        def select_all(arel, name = nil, binds = [])
+        def select_all(arel, name = nil, binds = [], preparable: nil)
           if arel.respond_to?(:locked) && arel.locked
             # SELECT ... FOR UPDATE queries should be sent to the primary.
             write_using_load_balancer(:select_all, [arel, name, binds],

ee/spec/lib/gitlab/database/load_balancing/connection_proxy_spec.rb

@@ -12,6 +12,13 @@ describe Gitlab::Database::LoadBalancing::ConnectionProxy do
   end
 
   describe '#select_all' do
+    let(:override_proxy) { ActiveRecord::Base.connection.class }
+
+    # We can't use :Gitlab::Utils::Override because this method is dynamically prepended
+    it 'method signatures match', :rails5 do
+      expect(proxy.method(:select_all).parameters).to eq(override_proxy.instance_method(:select_all).parameters)
+    end
+
     describe 'using a SELECT query' do
       it 'runs the query on a secondary' do
         arel = double(:arel)