Check for builder container in npm build

Former-commit-id: 156758bfa7

app/data/container-build/default-build.sh

@@ -1,6 +1,9 @@
 #!/usr/bin/env bash
 # Usage: default-build.sh <image-tag> [<repo-relative-path>]
 # if <repo-relative-path> is not supplied, the context is the directory where the Dockerfile lives
+if [[ -n "$CERC_SCRIPT_DEBUG" ]]; then
+    set -x
+fi
 if [[ $# -ne 2 ]]; then
     echo "Illegal number of parameters" >&2
     exit 1