Merge branch 'dm-batchloader-project' into 'master'

Include project in BatchLoader key to prevent returning blobs for the wrong project

Closes gitlab-ee#4325

See merge request gitlab-org/gitlab-ce!15936

app/models/blob.rb

@@ -77,9 +77,15 @@ class Blob < SimpleDelegator
   end
 
   def self.lazy(project, commit_id, path)
-    BatchLoader.for(commit_id: commit_id, path: path).batch do |items, loader|
-      project.repository.blobs_at(items.map(&:values)).each do |blob|
-        loader.call({ commit_id: blob.commit_id, path: blob.path }, blob) if blob
+    BatchLoader.for({ project: project, commit_id: commit_id, path: path }).batch do |items, loader|
+      items_by_project = items.group_by { |i| i[:project] }
+
+      items_by_project.each do |project, items|
+        items = items.map { |i| i.values_at(:commit_id, :path) }
+
+        project.repository.blobs_at(items).each do |blob|
+          loader.call({ project: blob.project, commit_id: blob.commit_id, path: blob.path }, blob) if blob
+        end
       end
     end
   end

spec/support/batch_loader.rb

+RSpec.configure do |config|
+  config.after do
+    BatchLoader::Executor.clear_current
+  end
+end