Only check CHANNEL_BRANCH if TESTNET_TAG is not set from buildkite (#3701)

ci/testnet-manager.sh

@@ -68,26 +68,29 @@ echo "SOLANA_METRICS_CONFIG: $SOLANA_METRICS_CONFIG"
 ci/channel-info.sh
 eval "$(ci/channel-info.sh)"
 
-case $TESTNET in
-testnet-edge|testnet-edge-perf)
+if [[ -n $TESTNET_TAG ]]; then
+  CHANNEL_OR_TAG=$TESTNET_TAG
+else
+  case $TESTNET in
+  testnet-edge|testnet-edge-perf)
     CHANNEL_OR_TAG=edge
     CHANNEL_BRANCH=$EDGE_CHANNEL
     ;;
-testnet-beta|testnet-beta-perf)
+  testnet-beta|testnet-beta-perf)
     CHANNEL_OR_TAG=beta
     CHANNEL_BRANCH=$BETA_CHANNEL
     ;;
-testnet|testnet-perf)
+  testnet|testnet-perf)
     CHANNEL_OR_TAG=$STABLE_CHANNEL_LATEST_TAG
     CHANNEL_BRANCH=$STABLE_CHANNEL
     ;;
-*)
+  *)
     echo "Error: Invalid TESTNET=$TESTNET"
     exit 1
     ;;
-esac
+  esac
 
-if [[ $BUILDKITE_BRANCH != "$CHANNEL_BRANCH" ]]; then
+  if [[ $BUILDKITE_BRANCH != "$CHANNEL_BRANCH" ]]; then
     (
       cat <<EOF
 steps:
@@ -102,6 +105,7 @@ steps:
 EOF
     ) | buildkite-agent pipeline upload
     exit 0
+  fi
 fi