Abort fuse integration test on error

Before, the fuse integration test was run and the tests were never
finished, because the testing code did not detect any errors when the
fusermount binary returned an error. This commit fixes it.

cmd/restic/integration_fuse_test.go

@@ -54,6 +54,10 @@ func waitForMount(dir string) error {
 }
 
 func cmdMount(t testing.TB, global GlobalOptions, dir string, ready, done chan struct{}) {
+	defer func() {
+		ready <- struct{}{}
+	}()
+
 	cmd := &CmdMount{global: &global, ready: ready, done: done}
 	OK(t, cmd.Execute([]string{dir}))
 	if TestCleanup {
@@ -104,7 +108,7 @@ func TestMount(t *testing.T) {
 		// We remove the mountpoint now to check that cmdMount creates it
 		RemoveAll(t, mountpoint)
 
-		ready := make(chan struct{}, 1)
+		ready := make(chan struct{}, 2)
 		done := make(chan struct{})
 		go cmdMount(t, global, mountpoint, ready, done)
 		<-ready