Include caret in CommitRange#reference_title

app/models/commit_range.rb

@@ -73,7 +73,7 @@ class CommitRange
 
   # Returns a String for use in a link's title attribute
   def reference_title
-    "Commits #{sha_from} through #{sha_to}"
+    "Commits #{sha_from_as_param} through #{sha_to}"
   end
 
   # Return a Hash of parameters for passing to a URL helper

spec/models/commit_range_spec.rb

@@ -49,9 +49,13 @@ describe CommitRange do
   end
 
   describe '#reference_title' do
-    it 'returns the correct String' do
+    it 'returns the correct String for three-dot ranges' do
       expect(range.reference_title).to eq "Commits #{sha_from} through #{sha_to}"
     end
+
+    it 'returns the correct String for two-dot ranges' do
+      expect(range2.reference_title).to eq "Commits #{sha_from}^ through #{sha_to}"
+    end
   end
 
   describe '#to_param' do