don't create the default section in search_helper

test plan:
 - Create a course via SIS import or Accounts page
   (not via front page, since this will enroll you as a teacher)
 - Go to the settings page for the created course and verify
   no sections were created

fixes CNVS-10683

Change-Id: I4ee7296cf45b44335a5fc49d701951e079800b20
Reviewed-on: https://gerrit.instructure.com/29189
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Bracken Mosbacker <bracken@instructure.com>
Product-Review: Bracken Mosbacker <bracken@instructure.com>
QA-Review: Nathan Rogowski <nathan@instructure.com>

app/helpers/search_helper.rb

@@ -44,7 +44,7 @@ module SearchHelper
             :state => type == :current ? :active : (course.recently_ended? ? :recently_active : :inactive),
             :available => type == :current && course.available?,
             :permissions => course.grants_rights?(@current_user),
-            :default_section_id => course.default_section.id
+            :default_section_id => course.default_section(no_create: true).try(:id)
           }
         end
       end

app/models/course.rb

@@ -1726,7 +1726,7 @@ class Course < ActiveRecord::Base
     if !section && opts[:include_xlists]
       section = CourseSection.active.where(:nonxlist_course_id => self).order(:id).first
     end
-    if !section
+    if !section && !opts[:no_create]
       section = course_sections.build
       section.default_section = true
       section.course = self

spec/models/course_spec.rb

@@ -3765,3 +3765,18 @@ describe Course, "multiple_sections?" do
     @course.multiple_sections?.should be_true
   end
 end
+
+describe Course, "default_section" do
+  it "should create the default section" do
+    c = Course.create!
+    s = c.default_section
+    c.course_sections.pluck(:id).should eql [s.id]
+  end
+
+  it "unless we ask it not to" do
+    c = Course.create!
+    s = c.default_section(no_create: true)
+    s.should be_nil
+    c.course_sections.pluck(:id).should be_empty
+  end
+end