Support a way to defer moving a temp file when we need to shuffle directories

[pcn]

Since sometimes directories grow, and moving them is necessary, moving a directory should be made safe. I'd like to have something like

sudo touch destination-defer && sudo mv destination destination-old && sudo mkdir destination && sudo chown user:group destination && sudo rm destination-defer

This would be to provide something like a 10 second window - these operations should never take very long on local disk. The defer, if left in place by accident, should elicit warnings in the log, but shouldn't prevent operation 10 seconds after it's created based on what I'm thinking right now.