Don't break rolling back when a namespace or project was renamed

lib/gitlab/database/rename_reserved_paths_migration/v1/rename_namespaces.rb

@@ -43,15 +43,15 @@ module Gitlab
             reverts_for_type('namespace') do |path_before_rename, current_path|
               matches_path = MigrationClasses::Route.arel_table[:path].matches(current_path)
               namespace = MigrationClasses::Namespace.joins(:route)
-                            .where(matches_path).first.becomes(MigrationClasses::Namespace)
+                            .where(matches_path).first&.becomes(MigrationClasses::Namespace)
 
               if namespace
                 perform_rename(namespace, current_path, path_before_rename)
 
                 rename_namespace_dependencies(namespace, current_path, path_before_rename)
               else
-                say "Couldn't rename namespace##{namespace.id} from #{current_path} "\
-                    " back to #{path_before_rename}, namespace no longer exists"
+                say "Couldn't rename namespace from #{current_path} back to #{path_before_rename} "\
+                    "namespace was renamed, or no longer exists at the expected path"
               end
             end
           end

lib/gitlab/database/rename_reserved_paths_migration/v1/rename_projects.rb

@@ -38,8 +38,10 @@ module Gitlab
 
                 move_project_folders(project, current_path, path_before_rename)
               else
-                say "Couldn't rename project##{project.id} from #{current_path} "\
-                    "back to #{path_before_rename}, project no longer exists"
+                say "Couldn't rename Project from #{current_path} back to "\
+                    "#{path_before_rename}, project was renamed or no longer "\
+                    "exists at the expected path."
+
               end
             end
           end

spec/lib/gitlab/database/rename_reserved_paths_migration/v1/rename_namespaces_spec.rb

@@ -278,5 +278,12 @@ describe Gitlab::Database::RenameReservedPathsMigration::V1::RenameNamespaces, :
 
       expect(File.directory?(expected_path)).to be_truthy
     end
+
+    it "doesn't break when the namespace was renamed" do
+      subject.rename_namespace(namespace)
+      namespace.update_attributes!(path: 'renamed-afterwards')
+
+      expect { subject.revert_renames }.not_to raise_error
+    end
   end
 end

spec/lib/gitlab/database/rename_reserved_paths_migration/v1/rename_projects_spec.rb

@@ -149,5 +149,12 @@ describe Gitlab::Database::RenameReservedPathsMigration::V1::RenameProjects, :tr
 
       expect(File.directory?(expected_path)).to be_truthy
     end
+
+    it "doesn't break when the project was renamed" do
+      subject.rename_project(project)
+      project.update_attributes!(path: 'renamed-afterwards')
+
+      expect { subject.revert_renames }.not_to raise_error
+    end
   end
 end