Fix a search for non-default branches when ES is enabled

CHANGELOG-EE.md

@@ -11,6 +11,7 @@ Please view this file on the master branch, on stable branches it's out of date.
   - Fix Git access panel for Wikis when Kerberos authentication is enabled (Borja Aparicio)
   - Decrease maximum time that GitLab waits for a mirror to finish !791 (Borja Aparicio)
   - User groups (that can be assigned as approvers)
+  - Fix a search for non-default branches when ES is enabled
 ## 8.12.7

lib/gitlab/elastic/project_search_results.rb

@@ -105,7 +105,11 @@ module Gitlab
               per_page: per_page
             )
           else
-            project.repository.find_commits_by_message(query).compact
+            Kaminari.paginate_array(
+              project.repository.find_commits_by_message(query).compact,
+              page: (page || 1).to_i,
+              per_page: per_page
+            )
           end
         end
       end

spec/lib/gitlab/elastic/project_search_results_spec.rb

@@ -63,6 +63,15 @@ describe Gitlab::Elastic::ProjectSearchResults, lib: true do
     end
   end
+  describe "search for commits in non-default branch" do
+    it "finds needed commit" do
+      project = create :project
+
+      result = Gitlab::Elastic::ProjectSearchResults.new(user, "initial", project.id, 'test')
+      expect(result.commits_count).to eq(1)
+    end
+  end
+
   describe 'confidential issues' do
     let(:query) { 'issue' }
     let(:author) { create(:user) }