bug#40974: 28.0.50; Prevent gnus registry from making entries when it shouldn't

[Eric Abrahamsen]

Eric Abrahamsen <eric@ericabrahamsen.net> writes:

> The function `gnus-registry-handle-action' is meant to handle message
> entries when messages are being moved/copied/deleted. Code comments
> indicate that if a message is being "moved to nowhere" it's actually
> being deleted, but the code doesn't actually delete the entry. In fact,
> because it unilaterally creates an entry before checking what to do with
> it, but then never deletes it, it will *create* entries for messages
> being deleted, or moved into groups that should be ignored.
>
> The attached patch confirms that registry information about the message
> should actually be kept, before keeping it.

Pushed to master.