Thanks for the feedback! We are working on enabling this feature.
JasonJim Berg commented
App Service Plans are what we have to pay for each month. It doesn't cost anything to create an app service. We use a separate app service for our Dev, Stage, UAT, and Demo environments running in the same App Service plan. Each one has its own predeploy slot so we can stage the app before deploying to the "production" slot of the environment. Trying to configure all of your environments in a single app service is obviously a management nightmare.
I do, however, need a copy feature. My problem is that I want to be able to setup a predeploy slot for a WordPress site and unfortunately WordPress maintains uploaded content in a folder under wwwroot. I need a way to copy those files from the production slot or vice versa. Just having a swap would remove all of those files. A feature to sync specific directories between slots would be very useful. Is there anything like that available now? Or the ability to configure a virtual directory that points to a directory shared by every slot?