Downloads and timeouts leave orphaned carts laying about

[karcaw]

Pacifica Core Software versions

pacifica-cli 0.4.0
pacifica-downloader 0.3.5

Platform Details

any

Scenario:

When a download times out as in pacifica/pacifica-python-downloader#24, or in other cases of failure, the cart that was created is now orphaned. And since it probably still staging, it is now blocking other cart creation processes. If the user gets the error, he is just going to retry, which just starts another cart which has a lower chance of even starting a stage before the timeout will happen.
see pacifica/pacifica-python-downloader#25 as well

Steps to Reproduce:

try and download a large(>1TB) cart that times out
or just download a small cart, it still orphans it.

Expected Result:

timeouts and other errors should be handled better by cleaning up the carts.
once a download is complete, delete the cart so that space is reclaimed on the storage backends.