message: ensure that classifier() classes aren't duplicated
diff: @@ -35,6 +35,10 @@ const map = createMapperWithPropTypes({
  export default map
  +function unique(values) {
  + return values.filter((v, i) => values.indexOf(v) === i)
  +}
  +
  export function classifier(propsToMap) {
  return ({className: baseClassName, ...props}) => {
  const mapped = {}
  @@ -54,7 +58,8 @@ export function classifier(propsToMap) {
  mapped[key] = props[key]
  }
  }
  - const className = classnames(baseClassName, ...classes).trim()
  + const classNames = classnames(baseClassName, ...classes).trim().split(' ')
  + const className = unique(classNames).join(' ')
  return className ? Object.assign(mapped, {className}) : mapped
  }
  }
  