MSR on Swarm one node to multi node scaling failure

The RethinkDB node can fail when scaling MSR on Swarm on a new cluster from one node to several nodes, resulting in the generation of the following error message during execution of scale command:

level=fatal msg="polling failed with 40 attempts 1s apart: service
\"msr_msr-rethinkdb\" is not yet ready"

To prevent such a failure, pre-pull RethinkDB images on all nodes. To do so, run following command on each node in a Swarm cluster:

docker pull