Browser automatically requesting favicon.ico

I wrote a http server using Google's GO Language. However the problem I confronted is not related to the language itself.

I think in certain situations, browsers automatically request favicon.ico as a little icon in the address bar. But my http server fails to properly handle this situation and causes itself to stuck.

It is not the same if I use nc to send request. Simply use "nc IP PORT" to connect, and then:
GET /test.html HTTP/1.0
and hit Enter two times
nc just sends and receives raw data, thus no automatic icon request. So my http server works in such situation with bug in it.