Petrified:
{
    "name": "hello-stratum",
    "kind": "stratum",
    "chunks": [
        {
            "name": "hello",
            "repo": "test:hello",
            "ref": "f4d032b42c0134e67bdf19a43fa99072493667d7",
            "build-depends": [],
            "unpetrify-ref": "master"
        },
        {
            "name": "goodbye",
            "repo": "test:goodbye",
            "ref": "test/petrify",
            "build-depends": []
        }
    ]
}

Unpetrified:
{
    "name": "hello-stratum",
    "kind": "stratum",
    "chunks": [
        {
            "name": "hello",
            "repo": "test:hello",
            "ref": "master",
            "build-depends": []
        },
        {
            "name": "goodbye",
            "repo": "test:goodbye",
            "ref": "test/petrify",
            "build-depends": []
        }
    ]
}