message: Kokoro related change for switching `nighlty-2.x` to the `nightly` and removing older `nightly` which was pointing to nightly-1.15.
diff: @@ -46,7 +46,7 @@ function ctpu_up {
  local name="kokoro-tpu-${RANDOM}"
  local zone="us-central1-c"
  local size="v2-8"
  - local version="nightly-2.x"
  + local version="nightly"
  local project # Project automatically detected from environment.
  local gcp_network # Network needed only if project default is Legacy.
  