Ensure branch cleanup regardless of whether the import process succeeds

CHANGELOG

@@ -32,6 +32,9 @@ v 8.9.0 (unreleased)
   - Cache project build count in sidebar nav
   - Reduce number of queries needed to render issue labels in the sidebar
 
+v 8.8.4 (unreleased)
+  - Ensure branch cleanup regardless of whether the GitHub import process succeeds
+
 v 8.8.3
   - Fix 404 page when viewing TODOs that contain milestones or labels in different projects. !4312
   - Fixed JS error when trying to remove discussion form. !4303

lib/gitlab/github_import/importer.rb

@@ -89,11 +89,11 @@ module Gitlab
           end
         end
 
-        delete_refs(branches_removed)
-
         true
       rescue ActiveRecord::RecordInvalid => e
         raise Projects::ImportService::Error, e.message
+      ensure
+        delete_refs(branches_removed)
       end
 
       def create_refs(branches)