Fixes tags:deploy command for images that contain ONBUILD directive

Fixes dokku#4226

plugins/builder-dockerfile/builder-release

@@ -15,7 +15,11 @@ trigger-builder-dockerfile-builder-release() {
   plugn trigger pre-release-dockerfile "$APP" "$IMAGE_TAG"
 
   local IMAGE=$(get_app_image_name "$APP" "$IMAGE_TAG")
-  echo "FROM $IMAGE" | suppress_output "$DOCKER_BIN" image build --label=com.dokku.image-stage=release --label=com.dokku.app-name=$APP --label=org.label-schema.schema-version=1.0 --label=org.label-schema.vendor=dokku --label=dokku -t "$IMAGE" -
+  if "$DOCKER_BIN" image history --format "{{ json . }}" "$IMAGE" | grep  -q "ONBUILD"; then
+    dokku_log_warn "Image contains ONBUILD directive(s), skipping re-labeling"
+  else
+    echo "FROM $IMAGE" | suppress_output "$DOCKER_BIN" image build --label=com.dokku.image-stage=release --label=com.dokku.app-name=$APP --label=org.label-schema.schema-version=1.0 --label=org.label-schema.vendor=dokku --label=dokku -t "$IMAGE" -
+  fi
   plugn trigger post-release-dockerfile "$APP" "$IMAGE_TAG"
 }