Migrate to Project#empty_repo?

changelogs/unreleased/zj-empty-repo-importer.yml

+---
+title: Fix GitHub importer using removed interface
+merge_request:
+author:
+type: fixed

lib/gitlab/github_import/importer/repository_importer.rb

@@ -29,7 +29,7 @@ module Gitlab
             # this code, e.g. because we had to retry this job after
             # `import_wiki?` raised a rate limit error. In this case we'll skip
             # re-importing the main repository.
-            if project.repository.empty_repo?
+            if project.empty_repo?
               import_repository
             else
               true

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

@@ -70,7 +70,7 @@ describe Gitlab::GithubImport::Importer::RepositoryImporter do
 
   describe '#execute' do
     it 'imports the repository and wiki' do
-      expect(repository)
+      expect(project)
         .to receive(:empty_repo?)
         .and_return(true)
 
@@ -93,7 +93,7 @@ describe Gitlab::GithubImport::Importer::RepositoryImporter do
     end
 
     it 'does not import the repository if it already exists' do
-      expect(repository)
+      expect(project)
         .to receive(:empty_repo?)
         .and_return(false)
 
@@ -115,7 +115,7 @@ describe Gitlab::GithubImport::Importer::RepositoryImporter do
     end
 
     it 'does not import the wiki if it is disabled' do
-      expect(repository)
+      expect(project)
         .to receive(:empty_repo?)
         .and_return(true)
 
@@ -137,7 +137,7 @@ describe Gitlab::GithubImport::Importer::RepositoryImporter do
     end
 
     it 'does not import the wiki if the repository could not be imported' do
-      expect(repository)
+      expect(project)
         .to receive(:empty_repo?)
         .and_return(true)