kubeadm: reset don't unmount /var/lib/kubelet if it is mounted

Previous PR that fixes this
https://github.com/kubernetes/kubernetes/pull/71663

Signed-off-by: Thomas Tanaka <thomas.tanaka@gmail.com>

cmd/kubeadm/app/cmd/phases/reset/unmount_linux.go

@@ -32,6 +32,12 @@ func unmountKubeletDirectory(absoluteKubeletRunDirectory string) error {
 	if err != nil {
 		return err
 	}
+
+	if !strings.HasSuffix(absoluteKubeletRunDirectory, "/") {
+		// trailing "/" is needed to ensure that possibly mounted /var/lib/kubelet is skipped
+		absoluteKubeletRunDirectory += "/"
+	}
+
 	mounts := strings.Split(string(raw), "\n")
 	for _, mount := range mounts {
 		m := strings.Split(mount, " ")