`pod-exec` Fails with 403

When using the following command:
`api.v1.namespaces('kube-system').pods(albPod.name).exec.get({ qs: { command: ['nginx', '-t'], container: 'nginx-ingress', stdout: true, stderr: true } });`
I get the following error:
```
{ Error: Unexpected server response: 403
at ClientRequest.req.on (node_modules/ws/lib/websocket.js:535:5)
at emitOne (events.js:116:13)
at ClientRequest.emit (events.js:211:7)
at HTTPParser.parserOnIncomingClient (_http_client.js:544:21)
at HTTPParser.parserOnHeadersComplete (_http_common.js:117:17)
at TLSSocket.socketOnData (_http_client.js:440:20)
at emitOne (events.js:116:13)
at TLSSocket.emit (events.js:211:7)
at addChunk (_stream_readable.js:263:12)
at readableAddChunk (_stream_readable.js:250:11) messages: [] }
```
This is the same failure for both `get` and `post`. I have tested using `config.fromKubeconfig(process.env.KUBECONFIG)` but have yet to try using `config.getInCluster()` but I do not think this is an auth issue. I am able to successfully use `kubectl` to get the `nginx -t` output like so:
`kubectl exec -in kube-system albPod.name -c nginx-ingress -- bash -c 'nginx -t'`

My only guess is something to do with the websocket upgrade. I noticed the upgrade response that `kubectl` uses is the following:
```
Response Headers:
Connection: Upgrade
Upgrade: SPDY/3.1
X-Stream-Protocol-Version: v4.channel.k8s.io
```
while the code included here uses for `pod-exec` is using `base64.channel.k8s.io`.

Start by comparing the pod-exec WebSocket upgrade used by the supplied get and post calls with the SPDY/3.1 and channel headers reported by kubectl. Reproduce the 403 with the shown command and verify the change against kubectl's successful nginx -t output; done means both client methods no longer fail with 403.

Written by the indexing model from the issue text.