Add `wiki` extra namespace when repository is_wiki: true

app/models/repository.rb

@@ -1049,11 +1049,19 @@ class Repository
   end
 
   def cache
-    @cache ||= Gitlab::RepositoryCache.new(self)
+    @cache ||= if is_wiki
+                 Gitlab::RepositoryCache.new(self, extra_namespace: 'wiki')
+               else
+                 Gitlab::RepositoryCache.new(self)
+               end
   end
 
   def request_store_cache
-    @request_store_cache ||= Gitlab::RepositoryCache.new(self, backend: Gitlab::SafeRequestStore)
+    @request_store_cache ||= if is_wiki
+                               Gitlab::RepositoryCache.new(self, extra_namespace: 'wiki', backend: Gitlab::SafeRequestStore)
+                             else
+                               Gitlab::RepositoryCache.new(self, backend: Gitlab::SafeRequestStore)
+                             end
   end
 
   def tags_sorted_by_committed_date

spec/models/repository_spec.rb

@@ -2403,4 +2403,22 @@ describe Repository do
       repository.merge_base('master', 'fix')
     end
   end
+
+  describe '#cache' do
+    subject(:cache) { repository.send(:cache) }
+
+    it 'returns a RepositoryCache' do
+      expect(subject).to be_kind_of Gitlab::RepositoryCache
+    end
+
+    it 'when is_wiki it includes wiki as part of key' do
+      allow(repository).to receive(:is_wiki) { true }
+
+      expect(subject.namespace).to include('wiki')
+    end
+
+    it 'when is_wiki is false extra_namespace is nil' do
+      expect(subject.namespace).not_to include('wiki')
+    end
+  end
 end