Move language detection to mandatory

Closes https://gitlab.com/gitlab-org/gitaly/issues/732
Closes https://gitlab.com/gitlab-org/gitaly/issues/360

spec/lib/gitlab/git/repository_spec.rb

@@ -1688,41 +1688,33 @@ describe Gitlab::Git::Repository, seed_helper: true do
   end
 
   describe '#languages' do
-    shared_examples 'languages' do
-      it 'returns exactly the expected results' do
-        languages = repository.languages('4b4918a572fa86f9771e5ba40fbd48e1eb03e2c6')
-        expected_languages = [
-          { value: 66.63, label: "Ruby", color: "#701516", highlight: "#701516" },
-          { value: 22.96, label: "JavaScript", color: "#f1e05a", highlight: "#f1e05a" },
-          { value: 7.9, label: "HTML", color: "#e34c26", highlight: "#e34c26" },
-          { value: 2.51, label: "CoffeeScript", color: "#244776", highlight: "#244776" }
-        ]
+    it 'returns exactly the expected results' do
+      languages = repository.languages('4b4918a572fa86f9771e5ba40fbd48e1eb03e2c6')
+      expected_languages = [
+        { value: 66.63, label: "Ruby", color: "#701516", highlight: "#701516" },
+        { value: 22.96, label: "JavaScript", color: "#f1e05a", highlight: "#f1e05a" },
+        { value: 7.9, label: "HTML", color: "#e34c26", highlight: "#e34c26" },
+        { value: 2.51, label: "CoffeeScript", color: "#244776", highlight: "#244776" }
+      ]
 
-        expect(languages.size).to eq(expected_languages.size)
+      expect(languages.size).to eq(expected_languages.size)
 
-        expected_languages.size.times do |i|
-          a = expected_languages[i]
-          b = languages[i]
+      expected_languages.size.times do |i|
+        a = expected_languages[i]
+        b = languages[i]
 
-          expect(a.keys.sort).to eq(b.keys.sort)
-          expect(a[:value]).to be_within(0.1).of(b[:value])
+        expect(a.keys.sort).to eq(b.keys.sort)
+        expect(a[:value]).to be_within(0.1).of(b[:value])
 
-          non_float_keys = a.keys - [:value]
-          expect(a.values_at(*non_float_keys)).to eq(b.values_at(*non_float_keys))
-        end
-      end
-
-      it "uses the repository's HEAD when no ref is passed" do
-        lang = repository.languages.first
-
-        expect(lang[:label]).to eq('Ruby')
+        non_float_keys = a.keys - [:value]
+        expect(a.values_at(*non_float_keys)).to eq(b.values_at(*non_float_keys))
       end
     end
 
-    it_behaves_like 'languages'
+    it "uses the repository's HEAD when no ref is passed" do
+      lang = repository.languages.first
 
-    context 'with rugged', :skip_gitaly_mock do
-      it_behaves_like 'languages'
+      expect(lang[:label]).to eq('Ruby')
     end
   end