Only rename exact matches for the route

The only path we need to rename is the exact match `old_path` and
child matches `old_path/%` instead of `old_path` wich would rename
routes that just look similar.

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

@@ -41,7 +41,9 @@ module Gitlab
                                             new_full_path)
             update_column_in_batches(:routes, :path, replace_statement)  do |table, query|
-              query.where(MigrationClasses::Route.arel_table[:path].matches("#{old_full_path}%"))
+              path_or_children = table[:path].eq(old_full_path)
+                                   .or(table[:path].matches("#{old_full_path}/%"))
+              query.where(path_or_children)
             end
           end

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

@@ -107,6 +107,15 @@ describe Gitlab::Database::RenameReservedPathsMigration::V1::RenameBase do
         expect(new_path).to eq('the-path0')
       end
+      it "doesn't rename routes that start with a similar name" do
+        other_namespace = create(:namespace, path: 'the-path-but-not-really')
+        project = create(:empty_project, path: 'the-project', namespace: other_namespace)
+
+        subject.rename_path_for_routable(migration_namespace(namespace))
+
+        expect(project.route.reload.path).to eq('the-path-but-not-really/the-project')
+      end
+
       context "the-path namespace -> subgroup -> the-path0 project" do
         it "updates the route of the project correctly" do
           subgroup = create(:group, path: "subgroup", parent: namespace)