Mongoose bug: SchemaType Boolean tries to convert input

bug.js

mongoose = require("mongoose")

mongoose.connect("mongodb://localhost/bug")
let db = mongoose.connection
db.on('error', (err) => {
	return console.error('Connection error:', err)
})

testSchema = mongoose.Schema({
	test: {
		type: String
	},
	bool: {
		type: Boolean
	}
})

let Test = mongoose.model('Test', testSchema)

		new Test({
			test: 'bool true',
			bool: true
		}).save()
	.then(() => {
		return new Test({
			test: 'bool false',
			bool: false
		}).save()
	})
	.then(() => {
		return new Test({
			test: 'string string',
			bool: "string"
		}).save()
	})
	.then(() => {
		return new Test({
			test: 'array empty',
			bool: []
		}).save()
	})
	.then(() => {
		return new Test({
			test: 'object empty',
			bool: {}
		}).save()
	})
	.then(() => {
		return Test.find()
	})
	.then((tests) => {
		// get results
		console.log(tests)

		// clean up db for next run
		for (let test of tests) {
			test.remove()
		}
	})

package.json

{
  "name": "bug-report",
  "version": "1.0.0",
  "description": "",
  "main": "bug.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "mongoose": "^4.9.6"
  }
}

workaround.js

testSchema = new mongoose.Schema({
  propertyThatAcceptsABoolean: {
		type: mongoose.Schema.Types.Mixed,
		validate: (input) => {
			return input === true || input === false
		}
	}
})

// We use schemaType mixed because it leaves the input untouched,
// then we define a custom validator that only resolves if the input is a (real) boolean.
// You can change the condition to also accept values like "true", "false", 0, 1...