quick-provision: disable tar timestamp warning

Otherwise tar may produce thousands lines of warning if the DUT's clock
is out of sync.

BUG=b:170635511
TEST=None

Change-Id: Ib01eabf2efb7a8c6813341cdf1177b23d684c4a8
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/dev-util/+/2717273
Auto-Submit: Kuang-che Wu <kcwu@chromium.org>
Tested-by: Kuang-che Wu <kcwu@chromium.org>
Commit-Queue: Kuang-che Wu <kcwu@chromium.org>
Reviewed-by: Amin Hassani <ahassani@chromium.org>
Reviewed-by: Jae Hoon Kim <kimjae@chromium.org>
diff --git a/quick-provision/quick-provision b/quick-provision/quick-provision
index a4a00b4..29a715c 100755
--- a/quick-provision/quick-provision
+++ b/quick-provision/quick-provision
@@ -187,7 +187,8 @@
   info "Stateful update"
   post_status "DUT: Stateful update"
   get_url_to_stdout "${url}" |
-    tar --ignore-command-error --overwrite --directory="${STATEFUL_DIR}" -xzf -
+    tar --ignore-command-error --overwrite --directory="${STATEFUL_DIR}" \
+      --warning=no-timestamp -xzf -
   local pipestatus=("${PIPESTATUS[@]}")
   if [[ "${pipestatus[0]}" -ne "0" ]]; then
     die "Retrieving ${url} failed. (statuses ${pipestatus[*]})"