When objects that reside in a manual eZ Flow block are deleted from the content tree, they are not removed from the ezm_pool table.

Clearing the cache or running the ezflow cronjob don't seem to help and the user must manually go in and remove each row that references a deleted item.

Steps to reproduce

1. Edit the frontpage node that is bundled with eZ Flow.
2. Add nodes to a manual block.
3. Sending for publishing.
4. Delete the nodes that were added in step #2 from the content tree, bypassing the trash.
5. Edit the frontpage node referenced in step #1. The manual block will have empty rows where the nodes used to be. These empty rows reference the deleted items and are listed as Online.