[bbagent] Check returned builds from all UpdateBuilds before starting luciexe
[bbagent] Check returned builds from all UpdateBuilds before starting luciexe

Bug: 1031205
Change-Id: Ide2867a3f570873786b8c1765d7cbe56277114e3
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/luci-go/+/3573590
Reviewed-by: Yuanjun Huang <a5f4b8445ce5e958d19c0a7caeadcd07c9d18770@google.com>
Commit-Queue: Chan Li <332b6c56634d0f63001046c664a2370006a02420@chromium.org>
Reviewed-by: Robbie Iannucci <40f3d43a28ebae3cb819288542e1c84d73d962d5@chromium.org>

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