save user course sort preference in the right db instance

test plan: sanity check sorting courses on the Accounts page.
 The actual issue this commit fixes cannot be reproduced except
 in production-like environments with master/slave databases.

fixes CNVS-34303

Change-Id: I92211a766600bcf811bbc268c95b92b0924a67cb
Reviewed-on: https://gerrit.instructure.com/99524
Reviewed-by: James Williams  <jamesw@instructure.com>
QA-Review: Heath Hales <hhales@instructure.com>
Tested-by: Jenkins
Product-Review: Jeremy Stanley <jeremy@instructure.com>

Author: jstanley0

app/controllers/accounts_controller.rb

@@ -923,12 +923,13 @@ def courses_redirect
 
   def courses
     if authorized_action(@context, @current_user, :read)
+      order = sort_order # must be done on master because it persists in user preferences
       Shackles.activate(:slave) do
         load_course_right_side
         @courses = []
         @query = (params[:course] && params[:course][:name]) || params[:term]
         if @context && @context.is_a?(Account) && @query
-          @courses = @context.courses_name_like(@query, :order => sort_order, :term => @term,
+          @courses = @context.courses_name_like(@query, :order => order, :term => @term,
             :hide_enrollmentless_courses => @hide_enrollmentless_courses,
             :only_master_courses => @only_master_courses)
         end

spec/controllers/accounts_controller_spec.rb

@@ -249,6 +249,7 @@ def cross_listed_course
       course_with_teacher(:account => @account)
       Account.any_instance.expects(:fast_all_courses).with(has_entry(order: "courses.created_at DESC"))
       get 'show', :id => @account.id, :courses_sort_order => "created_at_desc", :format => 'html'
+      expect(@admin.reload.preferences[:course_sort]).to eq 'created_at_desc'
     end
 
     it 'can search and sort simultaneously' do
@@ -259,6 +260,7 @@ def cross_listed_course
       @account.courses.create! name: 'bleh Z'
       get 'courses', :account_id => @account.id, :course => { :name => 'blah' }, :courses_sort_order => 'name_desc', :format => 'html'
       expect(assigns['courses'].map(&:name)).to eq(['blah C', 'blah B', 'blah A'])
+      expect(@admin.reload.preferences[:course_sort]).to eq 'name_desc'
     end
   end