Push command progress don't count correctly

[fw2568]

The current implementation of the bytes transferred counter in the push command works by reporting all bytes read from the source stream.

However, this doesn't work properly if bytes are read multiple times, most likely because some were rejected by the backend hash check and are being repeated. In this case, the number of bytes read will keep increasing, even if we have already reached 100%.

The implementation should be updated to prevent this problem. One solution might be to add a new progress step for repeated transfers, or to reset the count in case of a repeat.

AB#598