remove ipv6 fallbackdelay leave it as default

cmd/http/dial_dnscache.go

@@ -44,9 +44,6 @@ func DialContextWithDNSCache(cache *DNSCache, baseDialCtx DialContext) DialConte
 		baseDialCtx = (&net.Dialer{
 			Timeout:   30 * time.Second,
 			KeepAlive: 30 * time.Second,
-			// If zero, Go defaults to '300ms', we will default to 100ms instead.
-			// https://tools.ietf.org/html/rfc6555
-			FallbackDelay: 100 * time.Millisecond,
 		}).DialContext
 	}
 	return func(ctx context.Context, network, host string) (net.Conn, error) {

cmd/http/dial_linux.go

@@ -68,9 +68,6 @@ func NewInternodeDialContext(dialTimeout time.Duration) DialContext {
 	return func(ctx context.Context, network, addr string) (net.Conn, error) {
 		dialer := &net.Dialer{
 			Timeout: dialTimeout,
-			// If zero, Go defaults to '300ms', we will default to 100ms instead.
-			// https://tools.ietf.org/html/rfc6555
-			FallbackDelay: 100 * time.Millisecond,
 			Control: func(network, address string, c syscall.RawConn) error {
 				return setInternalTCPParameters(c)
 			},
@@ -84,9 +81,6 @@ func NewCustomDialContext(dialTimeout time.Duration) DialContext {
 	return func(ctx context.Context, network, addr string) (net.Conn, error) {
 		dialer := &net.Dialer{
 			Timeout: dialTimeout,
-			// If zero, Go defaults to '300ms', we will default to 100ms instead.
-			// https://tools.ietf.org/html/rfc6555
-			FallbackDelay: 100 * time.Millisecond,
 			Control: func(network, address string, c syscall.RawConn) error {
 				return c.Control(func(fdPtr uintptr) {
 					// got socket file descriptor to set parameters.