> When loading descriptor caches, we would accidentally reinitialize the
> descriptor cache when seeing that one already exists. This should have
> only been initializing the cache when one does not exist. However this
> code itself is unnecessary as the act of looking up the cache to add to
> it will initialize it if it didn't already exist.
>
> This issue could be hit by trying to load a wallet that had imported a
> multisig descriptor. The wallet would fail to load.
>
> A test has been added to wallet_importdescriptors.py to catch this case.
> Another test case has also been added to check that loading a wallet
> with only single key descriptors works.
This is a backport of core#19441