Fail to decode yaml that has affinity with versions v3.9.x

[emailbob]

Describe the bug

Since kustomize 3.9.x when kustomize changed the way it manipulates YAML using the kyaml module I started getting this error

2021/02/01 16:46:53 failed to decode ynode: yaml: unmarshal errors: line 97: mapping key "affinity" already defined at line 30

When using the built in HelmChartInflationGenerator if the Helm values file has two affinities set for example

  affinity:
    podAntiAffinity:
      requiredDuringSchedulingIgnoredDuringExecution:
        - labelSelector:
            matchExpressions:
              - key: component
                operator: In
                values:
                  - server
              - key: app
                operator: In
                values:
                  - prometheus
          topologyKey: "kubernetes.io/hostname"
...
  affinity:
    podAntiAffinity:
      requiredDuringSchedulingIgnoredDuringExecution:
        - labelSelector:
            matchExpressions:
              - key: component
                operator: In
                values:
                  - alertmanager
              - key: app
                operator: In
                values:
                  - prometheus
          topologyKey: "kubernetes.io/hostname"

It will throw an error

If they are empty and set like this

affinity: {}
...
affinity: {}

It will work

Expected output

No error

Actual output

2021/02/01 16:46:53 failed to decode ynode: yaml: unmarshal errors:
  line 97: mapping key "affinity" already defined at line 30

Kustomize version

v3.9.1 and v3.9.2

Platform

All

Additional context

I rolled back to v3.8.9 and that version works

[Shell32-Natsu]

I believe this error is thrown by go-yaml. I suppose that a valid YAML file shouldn't have duplicate keys.

[rochacon]

Seems like this is a duplicate of #3480

[Shell32-Natsu]

@rochacon Thanks for pointing out. It's duplicate.

Duplicate of #3480