$ minikube start

# I cannot imagine that this is related to the problem, but
# I have the impression that the problem is not reproducible when
# the namespace has a short name.
$ kubectl create namespace hosted-application-development
# change minikube context in .kube/config to use namespace

$ kubectl apply -f client.yaml

$ kubectl apply -f mysql.yaml
# wait until mysql pod is ready

$ kubectl exec -it test-client-pod bash
# mysql -u user -ppw -h test-mysql
ERROR 2013 (HY000): Lost connection to MySQL server at 'reading final connect information', system error: 0
command terminated with exit code 1