Comment 3 for bug 1392810

It would be needed for environments with tighter access
control: ie egress against streams.canonical.com
not allowed (IIRC was the case for us, by the time
streams.c.c. was hosted at AWS), and/or if you wanted to
avoid any auto-update happening behind scenes IIUC.

FYI didn't try using upgrade-juju --upload-tools again.