[bbagent] Make a shallow copy of the build if we need to change it
[bbagent] Make a shallow copy of the build if we need to change it

Bug: 1356247
Change-Id: I407a4074d0795b2afdd1de88deec93cb368982e5
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/luci-go/+/3864223
Reviewed-by: Robbie Iannucci <40f3d43a28ebae3cb819288542e1c84d73d962d5@chromium.org>
Commit-Queue: Chan Li <332b6c56634d0f63001046c664a2370006a02420@chromium.org>

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