panic in etcdcli

This is a clone of issue OCPBUGS-675. The following is the description of the original issue:
—
Description of problem:

A cluster hit a panic in etcd operator in bootstrap:
I0829 14:46:02.736582 1 controller_manager.go:54] StaticPodStateController controller terminated
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x1e940ab]

goroutine 2701 [running]:
github.com/openshift/cluster-etcd-operator/pkg/etcdcli.checkSingleMemberHealth({0x29374c0, 0xc00217d920}, 0xc0021fb110)
github.com/openshift/cluster-etcd-operator/pkg/etcdcli/health.go:135 +0x34b
github.com/openshift/cluster-etcd-operator/pkg/etcdcli.getMemberHealth.func1()
github.com/openshift/cluster-etcd-operator/pkg/etcdcli/health.go:58 +0x7f
created by github.com/openshift/cluster-etcd-operator/pkg/etcdcli.getMemberHealth
github.com/openshift/cluster-etcd-operator/pkg/etcdcli/health.go:54 +0x2ac
Version-Release number of selected component (if applicable):

How reproducible:

Pulled up a 4.12 cluster and hit panic during bootstrap

Steps to Reproduce:

1.
2.
3.

Actual results:

panic as above

Expected results:

no panic

Additional info: