Revert "Fixup: make signal handlers a bit simpler."

cmd/alertmanager/main.go

@@ -555,11 +555,14 @@ func run() int {
 
 	var (
 		hup      = make(chan os.Signal, 1)
+		hupReady = make(chan bool)
 		term     = make(chan os.Signal, 1)
 	)
 	signal.Notify(hup, syscall.SIGHUP)
 	signal.Notify(term, os.Interrupt, syscall.SIGTERM)
 
+	go func() {
+		<-hupReady
 		for {
 			select {
 			case <-hup:
@@ -567,6 +570,15 @@ func run() int {
 				_ = configCoordinator.Reload()
 			case errc := <-webReload:
 				errc <- configCoordinator.Reload()
+			}
+		}
+	}()
+
+	// Wait for reload or termination signals.
+	close(hupReady) // Unblock SIGHUP handler.
+
+	for {
+		select {
 		case <-term:
 			level.Info(logger).Log("msg", "Received SIGTERM, exiting gracefully...")
 			return 0