Downloading times out; doesn't resume: "[28] Timeout was reached"

This same issue seems to have been reported in:

• freedesktop-sdk issue: freedesktop-sdk/freedesktop-sdk#33 (closed), logs: https://gitlab.com/freedesktop-sdk/freedesktop-sdk/-/jobs/54775812
• flatpak: https://github.com/flatpak/flatpak/issues/1196
• ostree: https://github.com/ostreedev/ostree/issues/878
• curl: https://github.com/curl/curl/issues/1618#issuecomment-353128709

I'm submitting this here as we are still reproducing the issue even using latest ostree. Also in case buildstream wanted to implement something about that (retries, etc...)