new: Print progress estimates only when we have sufficient information
Without this patch, it might happen that the remaining time or processing
rate were calculated just after start where nothing was processed yet.
This resulted into division by a very small number (or zero) and the
printed information was of little value.
Instead of printing nonsenses we print only that the operation is in
progress. The estimates will be printed later, after there is enough data.
projects / notmuch / commit