Ensure clean repository folder before importing

To avoid `9:CreateRepositoryFromBundle: target directory is non-empty`
exceptions from Gitaly, when importing a Project, if the repository
folder already exists, ensure to Destroy existing repository before
importing the new one.

lib/gitlab/import_export/repo_restorer.rb

@@ -14,10 +14,10 @@ module Gitlab
       def restore
         return true unless File.exist?(path_to_bundle)
 
+        ensure_repository_does_not_exist!
+
         repository.create_from_bundle(path_to_bundle)
       rescue => e
-        Repositories::DestroyService.new(repository).execute
-
         shared.error(e)
         false
       end
@@ -25,6 +25,16 @@ module Gitlab
       private
 
       attr_accessor :repository, :path_to_bundle, :shared
+
+      def ensure_repository_does_not_exist!
+        if repository.exists?
+          shared.logger.info(
+            message: %Q{Deleting existing "#{repository.path}" to re-import it.}
+          )
+
+          Repositories::DestroyService.new(repository).execute
+        end
+      end
     end
   end
 end

spec/lib/gitlab/import_export/repo_restorer_spec.rb

@@ -36,21 +36,20 @@ RSpec.describe Gitlab::ImportExport::RepoRestorer do
       expect(subject.restore).to be_truthy
     end
 
-    context 'when the repository creation fails' do
-      before do
-        allow_next_instance_of(Repositories::DestroyService) do |instance|
+    context 'when the repository already exists' do
+      it 'deletes the existing repository before importing' do
+        allow(project.repository).to receive(:exists?).and_return(true)
+        allow(project.repository).to receive(:path).and_return('repository_path')
+
+        expect_next_instance_of(Repositories::DestroyService) do |instance|
           expect(instance).to receive(:execute).and_call_original
         end
-      end
-
-      it 'logs the error' do
-        allow(project.repository)
-          .to receive(:create_from_bundle)
-          .and_raise('9:CreateRepositoryFromBundle: target directory is non-empty')
 
-        expect(shared).to receive(:error).and_call_original
+        expect(shared.logger).to receive(:info).with(
+          message: 'Deleting existing "repository_path" to re-import it.'
+        )
 
-        expect(subject.restore).to be_falsey
+        expect(subject.restore).to be_truthy
       end
     end
   end