Otherwise it happens if stlink can not be opened on start. Change-Id: I7088f10e61508dae230eccfe576a51498c92f5b8 Signed-off-by: Paul Fertser <fercerpav@gmail.com> Reviewed-on: http://openocd.zylin.com/2550 Tested-by: jenkins Reviewed-by: Andreas Färber <afaerber@suse.de> Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk> Reviewed-by: Stian Skjelstad <stian@nixia.no>