Handle `ECONNRESET` gracefully

[dscho]

When the connection is reset (typically by the server side), the common trick is to wait a little and then try again.

But we don't:

Downloading single artifact
Preparing to download the following artifacts:
- minimal-sdk (ID: 1273852098, Size: 95936760)
Error: Unable to download artifact(s): Failed to ListArtifacts: Unable to make request: ECONNRESET

[dscho]

Since we switched to using the rolling ci-artifacts Release in #965, this is less of a problem now, and I think we can just close it without doing anything about it.