[Swarming] work around slow calls in archive.py

test/test262/archive.py

Index: test/test262/archive.py
diff --git a/test/test262/archive.py b/test/test262/archive.py
index 8398e5171648e10c668d852b62fd8ba1b8cb77ad..c265b324215a9e76f3202bb11ad1bd42392ad152 100755
--- a/test/test262/archive.py
+++ b/test/test262/archive.py
@@ -8,10 +8,15 @@ import tarfile
 
 os.chdir(os.path.dirname(os.path.abspath(__file__)))
 
+# Workaround for slow grp and pwd calls.
+tarfile.grp = None
+tarfile.pwd = None
+
 def filter_git(tar_info):
   if tar_info.name.startswith(os.path.join('data', '.git')):
     return None
   else:
+    tar_info.uname = tar_info.gname = "test262"
     return tar_info
 
 with tarfile.open('data.tar', 'w') as tar: