Wait for process to exit when stopping

If a process has some cleanup with purge-on-delete defined, the purge
has to wait until the process actually exited. Otherwise it may happen
that the process got the signal, files are purged, but the process is
still writing some files in order to exit cleanly. This would lead to
some artefacts left on the filesystem.

internal/testhelper/sigintwait/sigintwait.go

@@ -0,0 +1,18 @@
+package main
+
+import (
+	"os"
+	"os/signal"
+	"time"
+)
+
+func main() {
+	// Wait for interrupt signal to gracefully shutdown the app
+	quit := make(chan os.Signal, 1)
+	signal.Notify(quit, os.Interrupt)
+	<-quit
+
+	time.Sleep(3 * time.Second)
+
+	os.Exit(255)
+}