first checkout test to be patched

scripts/src/ConverterCommand.php

@@ -176,6 +176,8 @@ class ConverterCommand extends Command {
       static::executeCommand("git checkout {$this->core_target_branch} -- composer");
       static::executeCommand("git checkout {$this->core_target_branch} -- core/composer.json");
       static::executeCommand("git checkout {$this->core_target_branch} -- core/misc/cspell/dictionary.txt");
+      // Checkout original version of file to be patched.
+      static::executeCommand("git checkout {$this->core_target_branch} -- core/tests/Drupal/BuildTests/Composer/Template/ComposerProjectTemplatesTest.php");
 
       // Check out files that will be patched.
       static::executeCommand("git checkout {$this->core_target_branch} -- core/lib/Drupal/Core/EventSubscriber/FinishResponseSubscriber.php");