Fix tests for pub global activate.

sdk/lib/_internal/pub/test/get/path/nonexistent_dir_test.dart

Index: sdk/lib/_internal/pub/test/get/path/nonexistent_dir_test.dart
diff --git a/sdk/lib/_internal/pub/test/get/path/nonexistent_dir_test.dart b/sdk/lib/_internal/pub/test/get/path/nonexistent_dir_test.dart
index 95698fc59a12a5a291bf2bcc0700e0ee9b70b7f4..6a983c4cca3d4566d1dfbfdb62aa55614332f605 100644
--- a/sdk/lib/_internal/pub/test/get/path/nonexistent_dir_test.dart
+++ b/sdk/lib/_internal/pub/test/get/path/nonexistent_dir_test.dart
@@ -4,6 +4,7 @@
 
 import 'package:path/path.dart' as path;
 
+import '../../../lib/src/exit_codes.dart' as exit_codes;
 import '../../descriptor.dart' as d;
 import '../../test_pub.dart';
 
@@ -18,8 +19,10 @@ main() {
       })
     ]).create();
 
-    pubGet(error: """Could not find package foo at "$badPath".
-Depended on by:
-- myapp 0.0.0""");
+    pubGet(error: """
+        Could not find package foo at "$badPath".
+        Depended on by:
+        - myapp 0.0.0""",
+        exitCode: exit_codes.UNAVAILABLE);
   });
 }