Double timeout for curling stateful.tgz.

BUG=b:174969227
TEST=None

Change-Id: I4def3993cbccf4aaa5d2c35fffe646e1e13bf2f9
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/autotest/+/2585658
Tested-by: David Haddock <dhaddock@chromium.org>
Reviewed-by: Nicolas Boichat <drinkcat@chromium.org>
Commit-Queue: Nicolas Boichat <drinkcat@chromium.org>
Auto-Submit: David Haddock <dhaddock@chromium.org>
diff --git a/server/cros/update_engine/update_engine_test.py b/server/cros/update_engine/update_engine_test.py
index 98d7804..8d734f7 100644
--- a/server/cros/update_engine/update_engine_test.py
+++ b/server/cros/update_engine/update_engine_test.py
@@ -676,7 +676,7 @@
         statefuldev_url = update_url.replace('update', 'static')
         statefuldev_url += '/stateful.tgz'
         cmd = [
-                'curl', '--silent', '--show-error', '--max-time', '300',
+                'curl', '--silent', '--show-error', '--max-time', '600',
                 statefuldev_url, '|', 'tar', '--ignore-command-error',
                 '--overwrite', '--directory', '/mnt/stateful_partition', '-xz'
         ]