Fix .batch_lfs_pointers accepting a lazy enumerator

lib/gitlab/git/blob.rb

@@ -70,11 +70,9 @@ module Gitlab
         # Returns array of Gitlab::Git::Blob
         # Does not guarantee blob data will be set
         def batch_lfs_pointers(repository, blob_ids)
-          return [] if blob_ids.empty?
-
           repository.gitaly_migrate(:batch_lfs_pointers) do |is_enabled|
             if is_enabled
-              repository.gitaly_blob_client.batch_lfs_pointers(blob_ids)
+              repository.gitaly_blob_client.batch_lfs_pointers(blob_ids.to_a)
             else
               blob_ids.lazy
                       .select { |sha| possible_lfs_blob?(repository, sha) }

lib/gitlab/gitaly_client/blob_service.rb

@@ -34,6 +34,8 @@ module Gitlab
       end
 
       def batch_lfs_pointers(blob_ids)
+        return [] if blob_ids.empty?
+
         request = Gitaly::GetLFSPointersRequest.new(
           repository: @gitaly_repo,
           blob_ids: blob_ids

spec/lib/gitlab/git/blob_spec.rb

@@ -268,6 +268,21 @@ describe Gitlab::Git::Blob, seed_helper: true do
         expect(blobs).to all( be_a(Gitlab::Git::Blob) )
       end
 
+      it 'accepts blob IDs as a lazy enumerator' do
+        blobs = described_class.batch_lfs_pointers(repository, [lfs_blob.id].lazy)
+
+        expect(blobs.count).to eq(1)
+        expect(blobs).to all( be_a(Gitlab::Git::Blob) )
+      end
+
+      it 'handles empty list of IDs gracefully' do
+        blobs_1 = described_class.batch_lfs_pointers(repository, [].lazy)
+        blobs_2 = described_class.batch_lfs_pointers(repository, [])
+
+        expect(blobs_1).to eq([])
+        expect(blobs_2).to eq([])
+      end
+
       it 'silently ignores tree objects' do
         blobs = described_class.batch_lfs_pointers(repository, [tree_object.oid])