Update CommitRange#to_reference to use full SHAs

We only want them shortened by the filter, which calls to_s

app/models/commit_range.rb

@@ -61,11 +61,14 @@ class CommitRange
   end
   def to_reference(from_project = nil)
+    # Not using to_s because we want the full SHAs
+    reference = sha_from + notation + sha_to
+
     if cross_project_reference?(from_project)
-      "#{project.to_reference}@#{to_s}"
-    else
-      to_s
+      reference = project.to_reference + '@' + reference
     end
+
+    reference
   end
   # Returns a String for use in a link's title attribute

spec/lib/gitlab/markdown/commit_range_reference_filter_spec.rb

@@ -9,8 +9,7 @@ module Gitlab::Markdown
     let(:commit2) { project.commit("HEAD~2") }
     it 'requires project context' do
-      expect { described_class.call('Commit Range 1c002d..d200c1', {}) }.
-        to raise_error(ArgumentError, /:project/)
+      expect { described_class.call('') }.to raise_error(ArgumentError, /:project/)
     end
     %w(pre code a style).each do |elem|

spec/models/commit_range_spec.rb

 require 'spec_helper'
 describe CommitRange do
+  describe 'modules' do
+    subject { described_class }
+
+    it { is_expected.to include_module(Referable) }
+  end
+
   let(:sha_from) { 'f3f85602' }
   let(:sha_to)   { 'e86e1013' }
@@ -11,10 +17,14 @@ describe CommitRange do
     expect { described_class.new("Foo") }.to raise_error
   end
-  describe 'modules' do
-    subject { described_class }
-    it { is_expected.to include_module(Referable) }
+  describe '#to_s' do
+    it 'is correct for three-dot syntax' do
+      expect(range.to_s).to eq "#{sha_from[0..7]}...#{sha_to[0..7]}"
+    end
+    it 'is correct for two-dot syntax' do
+      expect(range2.to_s).to eq "#{sha_from[0..7]}..#{sha_to[0..7]}"
+    end
   end
   describe '#to_reference' do
@@ -34,16 +44,6 @@ describe CommitRange do
     end
   end
-  describe '#to_s' do
-    it 'is correct for three-dot syntax' do
-      expect(range.to_s).to eq "#{sha_from[0..7]}...#{sha_to[0..7]}"
-    end
-
-    it 'is correct for two-dot syntax' do
-      expect(range2.to_s).to eq "#{sha_from[0..7]}..#{sha_to[0..7]}"
-    end
-  end
-
   describe '#reference_title' do
     it 'returns the correct String for three-dot ranges' do
       expect(range.reference_title).to eq "Commits #{sha_from} through #{sha_to}"