[Feature Request]: Add a way to distinguish whether a download is successful

[jyma]

What is the problem you're trying to solve?

When using singularity download for downloading, both successful and failed downloads will leave files in the --out-dir.
Is there a way to distinguish whether a download is successful?
Perhaps, during the download, a temporary filename like pieceid.car.temp should be used to identify it, and then it can be renamed to pieceid.car upon successful completion.

Describe the workaround you currently have

I don't have any workaround

Describe the feature you'd like

Perhaps, during the download, a temporary filename like pieceid.car.temp should be used to identify it, and then it can be renamed to pieceid.car upon successful completion.

Additional context

No response