Retry on pidfile read error

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

runtime/container_linux.go

@@ -313,7 +313,7 @@ func (c *container) writeEventFD(root string, cfd, efd int) error {
 func waitForStart(p *process, cmd *exec.Cmd) error {
 	for i := 0; i < 300; i++ {
 		if _, err := p.getPidFromFile(); err != nil {
-			if os.IsNotExist(err) {
+			if os.IsNotExist(err) || err == errInvalidPidInt {
 				alive, err := isAlive(cmd)
 				if err != nil {
 					return err