Undefined values incorrectly retained for refs that contain variables (generic rule refs)

[anakrish]

Undefined values are incorrectly retained and show up in output in the following rego:

package test

import rego.v1

principal := input.principal
action := input.action

p[principal][action] := 1 if {
  some a in []					    
}

q[principal][action] contains 1 if {
  some a in []					    
}

prodiuces

{
  "result": [
    {
      "expressions": [
        {
          "value": {
            "p": {
              "\"<undefined>\"": {}
            },
            "q": {
              "\"<undefined>\"": {
                "\"<undefined>\"": []
              }
            }
          },
          "text": "data.test",
          "location": {
            "row": 1,
            "col": 1
          }
        }
      ]
    }
  ]
}