Autoschema bug

@ParentSchemaCol = new Meteor.Collection('parentcol')
@SubSchemaCol = new Meteor.Collection('subcol')

subSchema = new SimpleSchema {
  autovalue: {
    type: Date
    autoValue: ->
      new Date()
  }
  value:{
    type: String
    autoValue: ->
      value = this.siblingField('autovalue')
      console.log(value)
      value?.toUTCString?() ? 'no value'
  }
}
parentSchema = new SimpleSchema {
  sub: {
    type: subSchema
    autoValue: ->
      {autovalue: new Date()}
  }
  value:{
    type: String
  }
}

ParentSchemaCol.attachSchema parentSchema
SubSchemaCol.attachSchema subSchema

parent_id = ParentSchemaCol.insert({value:'Test'}) // Works
ParentSchemaCol.update(parent_id,{$set:{value:'Breaks'}) // Breaks, autoValue in subschema doesn't set