[buildbucket] Fix a flaky test
[buildbucket] Fix a flaky test

R=9f116ddb1b24f6fc1916a676eb17161b6c07dfc1@chromium.org

Bug: 1014344
Change-Id: I227a01e3243290e053b402bce116e1db55cdbaa8
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/luci-go/+/1988538
Auto-Submit: Nodir Turakulov <ef4933a197ef7b4b3f55f1bec4942aead3637a2a@chromium.org>
Commit-Queue: Vadim Shtayura <9f116ddb1b24f6fc1916a676eb17161b6c07dfc1@chromium.org>
Reviewed-by: Vadim Shtayura <9f116ddb1b24f6fc1916a676eb17161b6c07dfc1@chromium.org>

luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go