github_import: Convert `update_repository()` to use `fetch_url()`

Convert `update_repository()` to use the newly introduced `fetch_url()`
function. This passes all required information to fetch the given URL to
Gitaly which transparently handles creation of the remote for us.

The feature is currently hidden behind the `:gitaly_fetch_remote_params`
feature flag.

lib/gitlab/github_import/importer/pull_requests_importer.rb

@@ -36,7 +36,11 @@ module Gitlab
           # updating the timestamp.
           project.update_column(:last_repository_updated_at, Time.zone.now)
 
+          if Feature.enabled?(:fetch_remote_params, project, default_enabled: :yaml)
+            project.repository.fetch_remote('github', url: project.import_url, refmap: Gitlab::GithubImport.refmap, forced: false)
+          else
             project.repository.fetch_remote('github', forced: false)
+          end
 
           pname = project.path_with_namespace
 

spec/lib/gitlab/github_import/importer/pull_requests_importer_spec.rb

@@ -3,7 +3,8 @@
 require 'spec_helper'
 
 RSpec.describe Gitlab::GithubImport::Importer::PullRequestsImporter do
-  let(:project) { create(:project, import_source: 'foo/bar') }
+  let(:url) { 'https://github.com/foo/bar.git' }
+  let(:project) { create(:project, import_source: 'foo/bar', import_url: url) }
   let(:client) { double(:client) }
 
   let(:pull_request) do
@@ -147,14 +148,10 @@ RSpec.describe Gitlab::GithubImport::Importer::PullRequestsImporter do
     end
   end
 
-  describe '#update_repository' do
+  shared_examples '#update_repository' do
     it 'updates the repository' do
       importer = described_class.new(project, client)
 
-      expect(project.repository)
-        .to receive(:fetch_remote)
-        .with('github', forced: false)
-
       expect_next_instance_of(Gitlab::Import::Logger) do |logger|
         expect(logger)
           .to receive(:info)
@@ -173,6 +170,28 @@ RSpec.describe Gitlab::GithubImport::Importer::PullRequestsImporter do
     end
   end
 
+  describe '#update_repository with :fetch_remote_params enabled' do
+    before do
+      stub_feature_flags(fetch_remote_params: true)
+      expect(project.repository)
+        .to receive(:fetch_remote)
+        .with('github', forced: false, url: url, refmap: Gitlab::GithubImport.refmap)
+    end
+
+    it_behaves_like '#update_repository'
+  end
+
+  describe '#update_repository with :fetch_remote_params disabled' do
+    before do
+      stub_feature_flags(fetch_remote_params: false)
+      expect(project.repository)
+        .to receive(:fetch_remote)
+        .with('github', forced: false)
+    end
+
+    it_behaves_like '#update_repository'
+  end
+
   describe '#update_repository?' do
     let(:importer) { described_class.new(project, client) }