[stable29] multi-instance object store tweaks

[leftybournes]

No description provided.

[icewind1991]

I'm not sure if a move command like this is the correct option. (Only setting the stored instance, not moving an actual object). Or if we want to extend https://github.com/nextcloud/multibucket_migrate instead, which does perform the object moving.

[icewind1991]

Outside of the move command the changes look good

[leftybournes]

I'm not sure if a move command like this is the correct option. (Only setting the stored instance, not moving an actual object). Or if we want to extend https://github.com/nextcloud/multibucket_migrate instead, which does perform the object moving.

I think extending multibucket_migrate is the way to go since that's already available instead of adding the move command.

[icewind1991]

Apart from changing it to only verify a small number of objects for the move command this looks good to go

[icewind1991]

In general, I would suggest throwing exceptions in validateForUser for anything but the expected "object not found" error to prevent confusing users with an error message that doesn't match the error.