Fixes #92- based on the reported version by the bootloader, avrdude sends a different message length for the STK_SET_DEVICE_EXT command
Fix a minor issue with the timeout logic:
bootloader might hang forever if flashing starts and something "bad" happens to the sender before the first DATA packet has been sent (e.g. power loss)
Description
avrdudesends a different message length for theSTK_SET_DEVICE_EXTcommandDATApacket has been sent (e.g. power loss)