So I encounter this weird issue where favicon.ico does not show up on my browser. No matter if I cleared my browser or restarted the browser, it doesn't work. And the trick below saves me some troubles.
Simply append a question mark in the quoted favicon.ico like:
<link rel="shortcut icon" href="favicon.ico?" type="image/x-icon" />
Magic, isn't it?
Thanks to solution from here, and detailed explanations are in the link too.