Try out the monkey patch to fix the middleware

which isn't properly cleaning up whenever something
is thrown, not raised. See:

https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/1402#note_25128108

config/initializers/fix_local_cache_middleware.rb

+module LocalCacheRegistryCleanupWithEnsure
+  LocalCacheRegistry =
+    ActiveSupport::Cache::Strategy::LocalCache::LocalCacheRegistry
+  LocalStore =
+    ActiveSupport::Cache::Strategy::LocalCache::LocalStore
+
+  def call(env)
+    LocalCacheRegistry.set_cache_for(local_cache_key, LocalStore.new)
+    response = @app.call(env)
+    response[2] = ::Rack::BodyProxy.new(response[2]) do
+      LocalCacheRegistry.set_cache_for(local_cache_key, nil)
+    end
+    cleanup_after_response = true # ADDED THIS LINE
+    response
+  rescue Rack::Utils::InvalidParameterError
+    [400, {}, []]
+  ensure # ADDED ensure CLAUSE to cleanup when something is thrown
+    LocalCacheRegistry.set_cache_for(local_cache_key, nil) unless
+      cleanup_after_response
+  end
+end
+
+ActiveSupport::Cache::Strategy::LocalCache::Middleware
+  .prepend(LocalCacheRegistryCleanupWithEnsure)