Arabic spotlight docker fails during build

[AhmedBytesBits]

Hi,
When tried to build from Dockerfile for arabic Spotlight it fails during the RUN command with following error message:

The command '/bin/sh -c apk add --no-cache curl && mkdir -p /opt/spotlight && cd /opt/spotlight && curl -O "http://$RELEASE_SERVER/spotlight/$RELEASE_FILENAME" && curl -O "http://$RELEASE_SERVER/2016-10/ar/model/$LANGUAGE_MODEL" && tar xvf $LANGUAGE_MODEL && rm $LANGUAGE_MODEL && apk del curl' returned a non-zero code: 1

Splitting RUN command to debug yields the following error:

tar: invalid tar magic
The command '/bin/sh -c tar xvf $LANGUAGE_MODEL' returned a non-zero code: 1

Any advises to fix this?