Output in transaction traces seem to be missing for delegatecall

[karalabe]

Inspecting a Ropsten delegatecall transaction trace for Parity https://ropsten.etherscan.io/vmtrace?txhash=0x5988b820495933d508e532a5b638b5e2d270481f7400af2e99740e87ccfd8de9&type=parity seems to indicate that no output was produced, however the go-ethereum traces seems to disagree:

{
  "type": "CALL",
  "from": "0x28622d50aa95e19deee2d7477a7885bc0864c64d",
  "to": "0xb9ed9083238737c15e99df144cec348485251438",
  "input": "0x54fd4d50",
  "output": "0x",
  "gas": "0x1df64",
  "gasUsed": "0x58c4",
  "value": "0x0",
  "calls": [
    {
      "type": "CALL",
      "from": "0xb9ed9083238737c15e99df144cec348485251438",
      "to": "0xb9ed9083238737c15e99df144cec348485251438",
      "input": "0x80ce60d10000000000000000000000000000000000000000000000000000000000000005",
      "output": "0x",
      "gas": "0x1d10f",
      "gasUsed": "0x1533",
      "value": "0x0"
    },
    {
      "type": "DELEGATECALL",
      "from": "0xb9ed9083238737c15e99df144cec348485251438",
      "to": "0xb9f5657e62f57cf62d44b571722a0ad7cbcfacac",
      "input": "0x54fd4d50",
      "output": "0x54fd4d5000000000000000000000000000000000000000000000000000000000",
      "gas": "0xd903",
      "gasUsed": "0x1bb4",
      "calls": [
        {
          "type": "CALL",
          "from": "0xb9ed9083238737c15e99df144cec348485251438",
          "to": "0xb9ed9083238737c15e99df144cec348485251438",
          "input": "0x80ce60d10000000000000000000000000000000000000000000000000000000000000006",
          "output": "0x",
          "gas": "0xcf57",
          "gasUsed": "0x1533",
          "value": "0x0"
        }
      ]
    },
    {
      "type": "CALL",
      "from": "0xb9ed9083238737c15e99df144cec348485251438",
      "to": "0xb9ed9083238737c15e99df144cec348485251438",
      "input": "0x80ce60d10000000000000000000000000000000000000000000000000000000000000007",
      "output": "0x",
      "gas": "0x19585",
      "gasUsed": "0x1533",
      "value": "0x0"
    }
  ]
}

The DELEGATECALL stack seems to contain 96 as the offset for the output and 32 as the length. Since the DELEGATECALL succeeds, I'd assume the output should also be reported.