renameCollection command `dropTarget` parameter not a bool in oplog

A rename collection, run from the shell, such as:
db.test.renameCollection("test2", true)
Will result in an oplog entry that contains:

  "o": {

    "renameCollection": "XXX",

    "to": "YYY",

    "dropTarget": true

  }

The following command will still drop the target collection, I assume because
{dropTarget: true} still evalulates to true.
db.test.renameCollection("test2", {dropTarget:true})

But the resulting oplog entry contains:

  "o": {

    "renameCollection": "XXX",

    "to": "YYY",

    "dropTarget": {

      "dropTarget": true

   }