Allow long filenames setting for customer tests (#50060)

dev/customer_testing/run_tests.dart

@@ -173,7 +173,11 @@ Future<bool> run(List<String> arguments) async {
     } finally {
       if (verbose)
         print('Deleting temporary directory...');
-      checkout.deleteSync(recursive: true);
+      try {
+        checkout.deleteSync(recursive: true);
+      } on FileSystemException {
+        print('Failed to delete "${checkout.path}".');
+      }
     }
     if (verbose)
       print('');
@@ -256,8 +260,8 @@ class TestFile {
 
   // (e-mail regexp from HTML standard)
   static final RegExp _email = RegExp(r'''^[a-zA-Z0-9.!#$%&'*+\/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$''');
-  static final RegExp _fetch1 = RegExp(r'^git clone https://github.com/[-a-zA-Z0-9]+/[-_a-zA-Z0-9]+.git tests$');
-  static final RegExp _fetch2 = RegExp(r'^git -C tests checkout [0-9a-f]+$');
+  static final RegExp _fetch1 = RegExp(r'^git(?: -c core.longPaths=true)? clone https://github.com/[-a-zA-Z0-9]+/[-_a-zA-Z0-9]+.git tests$');
+  static final RegExp _fetch2 = RegExp(r'^git(?: -c core.longPaths=true)? -C tests checkout [0-9a-f]+$');
 
   final List<String> contacts;
   final List<String> fetch;