[kevincox]

Ah, I did have a typo. But you also copied it wrong. I wrote this

    labels:
        - mylabel
        - {{ extraLabels | indent 4 }} # toJson doesn't work here.

Which has an extra `-` and as you pointed out would produce a nested list.

But I meant this which would merge the lists.

    labels:
        - mylabel
        {{ extraLabels | indent 4 }} # toJson doesn't work here.