Close io when Start fails

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

io.go

@@ -15,7 +15,14 @@ type IO struct {
 	Stdout   string
 	Stderr   string
 
-	closer io.Closer
+	closer *wgCloser
+}
+
+func (i *IO) Wait() {
+	if i.closer == nil {
+		return
+	}
+	i.closer.Wait()
 }
 
 func (i *IO) Close() error {
@@ -129,10 +136,17 @@ type ioSet struct {
 type wgCloser struct {
 	wg  *sync.WaitGroup
 	dir string
+	set []io.Closer
+}
+
+func (g *wgCloser) Wait() {
+	g.wg.Wait()
 }
 
 func (g *wgCloser) Close() error {
-	g.wg.Wait()
+	for _, f := range g.set {
+		f.Close()
+	}
 	if g.dir != "" {
 		return os.RemoveAll(g.dir)
 	}