Log current test iteration

This should help tell when we are deadlocking from test logs if we hit a problem in the future.

pipe_test.go

@@ -644,6 +644,8 @@ func TestListenConnectRace(t *testing.T) {
 			s.Close()
 		}
 		wg.Wait()
+
+		t.Logf("iteration %d", i)
 	}
 }
 
@@ -684,5 +686,7 @@ func TestCloseRace(t *testing.T) {
 		}
 		_ = c.Close()
 		_ = l.Close()
+
+		t.Logf("iteration %d", i)
 	}
 }