After restoring from a backup and retrying to upgrade from 9.1.5 to 10.0.0, I notice the following behaviour during an 'occ upgrade':
2017-04-28T00:04:16+10:00 Repair step: Upgrade app code from the marketplace
2017-04-28T00:04:16+10:00 Repair info: Fetching app from market: activity
2017-04-28T00:05:32+10:00 Repair info: Fetching app from market: comments
2017-04-28T00:06:49+10:00 Repair info: Fetching app from market: configreport
2017-04-28T00:08:05+10:00 Repair info: Fetching app from market: dav
2017-04-28T00:09:22+10:00 Repair info: Fetching app from market: federatedfilesharing
2017-04-28T00:10:38+10:00 Repair info: Fetching app from market: federation
2017-04-28T00:11:54+10:00 Repair info: Fetching app from market: files
I'm sure this shouldn't be so slow. The system in question is on a 100Mbit link to the world in a data centre :\