Don't overwrite setup state in async_set_domains_to_be_loaded

[emontnemery]

Proposed change

Don't overwrite setup state in async_set_domains_to_be_loaded

During startup, async_set_domains_to_be_loaded is called multiple times with sets of domains to indicate domains which will be loaded in each stage.
If a domain is passed in more than once, we need to ensure we don't overwrite the previously created future, or create a future for a domain which has already been set up to prevent the startup process from deadlocking.

CC @jpbede

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• Dependency upgrade
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[jpbede]

Nice, thanks a lot! 👍