Remove last instance variable in bundle_spec

Breakout method to a `support` file (will be reused elsewhere).

spec/bundle_spec.rb

@@ -5,14 +5,6 @@
   let(:revs)   { bundle_setup(:proj_revs) }
   let(:rumsey) { bundle_setup(:proj_rumsey) }
 
-  def bundle_setup(proj)
-    filename = "spec/test_data/project_config_files/#{proj}.yaml"
-    @ps = YAML.load(File.read(filename))
-    @ps['config_filename'] = filename
-    @ps['show_progress'] = false
-    PreAssembly::Bundle.new(@ps)
-  end
-
   describe "initialize() and other setup" do
     it "trims the trailing slash from the bundle directory" do
       expect(revs.bundle_dir).to eq('spec/test_data/bundle_input_a')
@@ -562,9 +554,8 @@ def bundle_setup(proj)
       expect(b.progress_log_file).to eq('spec/test_data/project_config_files/proj_sohp3_progress.yaml')
     end
 
-    it "sets the content_tag_override to the default value when not specified" do
+    it "sets content_tag_override to the default value when not specified" do
       expect(revs.project_style[:content_tag_override]).to be_falsey
-      expect(@ps['project_style'][:content_tag_override]).to be_nil
     end
 
     it "sets the staging_dir to the default value if not specified in the YAML" do

spec/support/bundle_setup.rb

@@ -0,0 +1,9 @@
+# @param [#to_s] proj basename of YAML fixture file
+# @return [PreAssembly::Bundle]
+def bundle_setup(proj)
+  filename = "spec/test_data/project_config_files/#{proj}.yaml"
+  ps = YAML.load(File.read(filename))
+  ps['config_filename'] = filename
+  ps['show_progress'] = false
+  PreAssembly::Bundle.new(ps)
+end