net/http: skip TestTransportRemovesDeadIdleConnections on Plan 9

Updates #15464.

Change-Id: If3221034bb10751c6fcf1fbeba401a879c18079f
Reviewed-on: https://go-review.googlesource.com/22513
Run-TryBot: David du Colombier <0intro@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/net/http/transport_test.go

@@ -439,6 +439,9 @@ func TestTransportMaxPerHostIdleConns(t *testing.T) {
 }
 
 func TestTransportRemovesDeadIdleConnections(t *testing.T) {
+	if runtime.GOOS == "plan9" {
+		t.Skip("skipping test; see https://golang.org/issue/15464")
+	}
 	defer afterTest(t)
 	ts := httptest.NewServer(HandlerFunc(func(w ResponseWriter, r *Request) {
 		io.WriteString(w, r.RemoteAddr)