Revert "(#501) make IP.String() method return something sensible"

This reverts commit b1c9612158.

net/net.go

@@ -357,10 +357,7 @@ func ParseIP(s string) IP {
 
 // String returns the string form of the IP address ip.
 func (ip IP) String() string {
-	if len(ip) < 4 {
-		return ""
-	}
-	return strconv.Itoa(int(ip[0])) + "." + strconv.Itoa(int(ip[1])) + "." + strconv.Itoa(int(ip[2])) + "." + strconv.Itoa(int(ip[3]))
+	return string(ip)
 }
 
 // Conn is a generic stream-oriented network connection.

net/net_test.go

@@ -1,14 +0,0 @@
-package net
-
-import (
-	"testing"
-
-	qt "github.com/frankban/quicktest"
-)
-
-func TestIPAddressString(t *testing.T) {
-	c := qt.New(t)
-	ipaddr := ParseIP("127.0.0.1")
-
-	c.Assert(ipaddr.String(), qt.Equals, "127.0.0.1")
-}