Skyplane does not perform inter-cloud small file transfers

[josephcolton]

Describe the bug
When I try to copy a small file (<=1GB) between two buckets in different clouds, it appears to be working and even asks for confirmation before a copy, but once I confirm the copy, it claims the Transfer is starting and ends the program.

To Reproduce
Steps to reproduce the behavior (please include the full Skyplane command you ran):

1. Copy a small file to a cloud bucket in AWS
2. Run a Skyplane command to copy that file to a cloud bucket at GCP
3. Wait until it ends
4. See nothing happened

Expected behavior
I expected to see the file copying and the time results. I also expected to see the file in the destination location.

Screenshots
joseph@sonnet ~ $ skyplane cp s3://aws.x.ap-southeast-2/zero-1gb.data gs://gcp_x_northamerica-northeast1/zero-1gb.data

---

/ | | / /\ \ / / ___ \ | / _ \ | \ | || |
\ --.| |/ / \ V /| |_/ / | / /_\ \| \| || |__ --. \ \ \ / | __/| | | _ || . ` || __|
/_/ / |\ \ | | | | | || | | || |\ || |__
_/_| _/ _/ _| _/_| |/_| _/____/

Logging to: /tmp/skyplane/transfer_logs/20230822_235228-9e0b5004/client.log
Using Skyplane version 0.3.2
Will transfer objects from aws:ap-southeast-2 to gcp:northamerica-northeast1-a
VMs to provision: 1x aws:ap-southeast-2, 1x gcp:northamerica-northeast1-a
Estimated egress cost: $0.11/GB
s3://aws.x.ap-southeast-2/zero-1gb.data => gs://gcp_x_northamerica-northeast1/zero-1gb.data (1.00GB)
Continue? [Y/n]: y
Transfer starting (Tip: Enable auto-confirmation with skyplane config set autoconfirm true)
joseph@sonnet ~ $

Transfer client log
joseph@sonnet ~ $ cat /tmp/skyplane/transfer_logs/20230822_235228-9e0b5004/client.log
23:52:28 [DEBUG] Using pipeline: <skyplane.api.pipeline.Pipeline object at 0x7f5ae1bd5270>
23:52:28 [DEBUG] [SkyplaneClient] Queued copy job CopyJob()
23:52:36 [DEBUG] Querying objects in s3://aws.x.ap-southeast-2
23:52:56 [DEBUG] User confirmed transfer
23:52:59 [DEBUG] Querying objects in s3://aws.x.ap-southeast-2

Environment info (please complete the following information):

• OS: Ubuntu 22.04.3 LTS
• Python version: 3.10.12
• Skyplane version: 0.3.2

Additional context
My guess is that the replicate_small_cp_cmd method does not handle inter-cloud copy operations, only intra-cloud copy operations.