Issue #3161320 by neclimdul, Beakerboy, smustgrave:...

Issue #3161320 by neclimdul, Beakerboy, smustgrave: Drupal\Tests\Composer\Plugin\VendorHardening\ConfigTest leaking configuration changes

core/tests/Drupal/Tests/Composer/Plugin/VendorHardening/ConfigTest.php

@@ -83,6 +83,8 @@ public function testRootMergeConfig() {
 
   /**
    * @covers ::getAllCleanupPaths
+   *
+   * @runInSeparateProcess
    */
   public function testMixedCaseConfigCleanupPackages() {
     // Root package has configuration in extra.