Docker-machine Executor attempts to continually remove a docker machine

Note: Solution in ~upstream https://github.com/docker/machine/pull/4317.

A customer (https://gitlab.my.salesforce.com/0016100000SEjM1) sees that a runner is attempted to be removed, and then it keeps attempting this:

Sep 18 09:58:57 ip-172-16-1-160 gitlab-ci-multi-runner[22481]: time="2017-09-18T09:58:57Z" level=warning msg="Removing machine" created=37.890726302s name=runner-f0094812-as-reserved-eu-west-1a-1505728699-8f48521b now=2017-09-18 09:58:57.198401546 +0000 UTC reason="Failed to create" used=37.890727499s
Sep 18 09:58:57 ip-172-16-1-160 gitlab-ci-multi-runner[22481]: time="2017-09-18T09:58:57Z" level=warning msg="Skipping machine removal, because it doesn't exist" created=37.890829529s name=runner-f0094812-as-reserved-eu-west-1a-1505728699-8f48521b reason="Failed to create" used=32.224µs
Sep 18 09:58:57 ip-172-16-1-160 gitlab-ci-multi-runner[22481]: time="2017-09-18T09:58:57Z" level=info msg="Machine removed" created=37.890863313s name=runner-f0094812-as-reserved-eu-west-1a-1505728699-8f48521b now=2017-09-18 09:58:57.198537302 +0000 UTC reason="Failed to create" retries=0 used=66.073µs
Sep 18 09:58:57 ip-172-16-1-160 gitlab-runner[22481]: time="2017-09-18T09:58:57Z" level=warning msg="Skipping machine removal,

Ultimately when they see this state, they use

docker-machine rm -f runner-f0094812-as-reserved-eu-west-1a-1505734081-d95aa7f7

to remove the runner.

Runer 9.5.4