Script fails when DOCKER_CERT_PATH is set to non-default location

[rmorrise]

My DOCKER_CERT_PATH in my environment is set to: D:\dev\docker_machine\machines\certs

However, when I run this script on my machine, I get the following output:

=====[default] Creating a new Docker daemon certificate=====
mv: cannot stat '/c/Users/rmorrise//.docker/machine/machines/default/server.pem': No such file or directory

I am on win7 x64 docker-machine version 0.12.2, build 9371605 Docker version 17.07.0-ce, build 8784753