Allow --clive-version to be omitted in build_instance.sh when --embedded-testnet is used

scripts/ci-helpers/build_instance.sh

@@ -28,7 +28,7 @@ print_help () {
     echo "OPTIONS:"
     echo "  --beekeeper-source-image=image_name Allows to specify image name containing a prebuilt beekeper tool"
     echo "  --base-image=image_name             Allows to specify an image name being use as a base of the one to be built"
-    echo "  --clive-version=version             Allows to specify a version of clive to be installed in the image"
+    echo "  --clive-version=version             Allows to specify a version of clive to be installed in the image (omitted if --embedded-testnet is used)"
     echo "  --embedded-testnet                  Allows to build a clive image having embedded a hived testnet inside (ready for immediate sanboxing run)"
     echo "  --image-path-suffix                 Allows to specify a suffix to be added to the image path, to organize images in a more structured directory-like way"
     echo "  --help                              Display this help screen and exit"
@@ -86,7 +86,14 @@ TST_REGISTRY=${REGISTRY:?"Missing arg #3 to specify target container registry"}
 
 TST_BEEKEEPER_IMAGE=${BEEKEEPER_IMAGE:?"Missing --beekeeper-source-image to specify beekeeper binary source"}
 TST_BASE_IMAGE=${BASE_IMAGE:?"Missing --base-image option to specify base image"}
-TST_CLIVE_VERSION=${CLIVE_VERSION:?"Missing --clive-version option to specify clive version"}
+
+if [ -z "$CLIVE_VERSION" ] && [ "$DOCKER_TARGET" != "embedded_testnet_instance" ];
+then
+  echo "ERROR: Missing --clive-version option to specify clive version to be installed"
+  echo
+  print_help
+  exit 2
+fi
 
 # Supplement a registry path by trailing slash (if needed)
 [[ "${REGISTRY}" != */ ]] && REGISTRY="${REGISTRY}/"