yq: Can't handle multiple yaml documents within one file

Given the following Kubernetes YAML configuration file:

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
   name: somename
spec:
   revisionHistoryLimit: 5
   minReadySeconds: 10
   strategy:
      type: RollingUpdate
      rollingUpdate:
         maxUnavailable: 0
         maxSurge: 1
   replicas: 1
   template:
      metadata:
         labels:
            microservice: somename
      spec: 
         containers:
         - name: serviceapi
           image: myimage:0.0.6
           ports:
           - containerPort: 8080
           env:
##### ENVIRONMENT VARIABLES
            - name: somename
              valueFrom:
                configMapKeyRef:
                   name: serviceapi-environment-configuration
                   key: somekey
---
apiVersion: v1
kind: Service
metadata:
  name: somename
  labels: 
     microservice: somename
spec:
   type: NodePort
   ports:
   - port: 8080
   selector:
      microservice: somename
---
apiVersion: v1
kind: ConfigMap
metadata:
  name: some-name
  namespace: default
data:
  someData: data

This command will work:

./yaml w -i myfile.yaml spec.template.spec.containers[0].image myimage:0.0.19

The image value will be replaced, however, the file will then change to this:

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
   name: somename
spec:
   revisionHistoryLimit: 5
   minReadySeconds: 10
   strategy:
      type: RollingUpdate
      rollingUpdate:
         maxUnavailable: 0
         maxSurge: 1
   replicas: 1
   template:
      metadata:
         labels:
            microservice: somename
      spec: 
         containers:
         - name: serviceapi
           image: myimage:0.0.19
           ports:
           - containerPort: 8080
           env:
##### ENVIRONMENT VARIABLES
            - name: somename
              valueFrom:
                configMapKeyRef:
                   name: serviceapi-environment-configuration
                   key: somekey

As you can see, the Services and ConfigMap sections (denoted with ---) have disappeared.