webapp:Parameter --configuration-source does not copy app settings and connection strings

I expected the `--configuration-source` parameter on `az webapp deployment slot create` command to copy app settings and connection strings to the new slot, but it doesn't.

Is there another way to achieve this using the CLI? Using the Azure Portal, it is possible to clone the configuration from another slot. It would be really useful if this functionality were also available from the CLI.

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* ID: ce9f5bf9-d178-de1a-645b-be6947a7c049
* Version Independent ID: cb7fb876-160c-e6d9-d473-7ac39b930b48
* Content: [az webapp deployment slot](https://docs.microsoft.com/en-us/cli/azure/webapp/deployment/slot?view=azure-cli-latest)
* Content Source: [latest/docs-ref-autogen/webapp/deployment/slot.yml](https://github.com/Azure/azure-docs-cli-python/blob/live/latest/docs-ref-autogen/webapp/deployment/slot.yml)
* Service: **app-service-web**
* GitHub Login: @rloutlaw
* Microsoft Alias: **routlaw**