types are showing in nested queries

[klahnakoski]

{
	"from":"treeherder.job_log",
	"where":{"exists":"failure_line.action"}
}

is revealing the datatyped column names:

"failure_line":{
        "action":{"~s~":"log"},
        "best_is_verified":{"~n~":0},
        "created":{"~n~":1524200942},
        "level":{"~s~":"ERROR"},
        "line":{"~n~":0},
        "modified":{"~n~":1524200942},
        "repository":{"~s~":"mozilla-esr52"},
        "~e~":1
    },