fix prefetch url (vercel#1154)

lib/link.js

@@ -61,8 +61,28 @@ export default class Link extends Component {
       })
   }
 
+  prefetch () {
+    if (!this.props.prefetch) return
+    if (typeof window === 'undefined') return
+
+    // Prefetch the JSON page if asked (only in the client)
+    const { pathname } = window.location
+    const href = resolve(pathname, this.props.href)
+    Router.prefetch(href)
+  }
+
+  componentDidMount () {
+    this.prefetch()
+  }
+
+  componentDidUpdate (prevProps) {
+    if (this.props.href !== prevProps.href) {
+      this.prefetch()
+    }
+  }
+
   render () {
-    let { children, prefetch } = this.props
+    let { children } = this.props
     // Deprecated. Warning shown by propType check. If the childen provided is a string (<Link>example</Link>) we wrap it in an <a> tag
     if (typeof children === 'string') {
       children = <a>{children}</a>
@@ -79,15 +99,6 @@ export default class Link extends Component {
       props.href = this.props.as || this.props.href
     }
 
-    // Prefetch the JSON page if asked (only in the client)
-    if (prefetch) {
-      if (typeof window !== 'undefined') {
-        const { pathname } = window.location
-        const href = resolve(pathname, props.href)
-        Router.prefetch(href)
-      }
-    }
-
     return React.cloneElement(child, props)
   }
 }

lib/prefetch.js

@@ -25,7 +25,7 @@ export default class LinkPrefetch extends React.Component {
     wantLinkPrefetch()
     const props = {
       ...this.props,
-      prefetch: this.props.prefetch === false ? this.props.prefetch : true
+      prefetch: this.props.prefetch !== false
     }
 
     return (<Link {...props} />)