Long-running uploads (multi-GB blobs over slow links) previously
produced silence between the start of the upload and the "Blob
stored" line at the end. Now we print:
Uploading blob: <hash> (<size>)
before the upload starts, and a heartbeat line at most every 15s:
uploading <hash>: <done>/<total> (NN%), <speed>/sec, <elapsed> elapsed, ETA <eta>
This gives the user visible progress on large uploads, especially
over SMB or remote storage where 10+ second stalls are normal.
sneak
b0747657e3