revisioning_scheduler_cron() tries to publish revisions of deleted nodes

Problem/Motivation

revisioning_scheduler_cron() tries to publish revisions of deleted nodes. It blindly invokes _revisioning_publish_revision(node_load($revision->revision_nid, $revision->revision_vid)) with the rows found in {revisioning_scheduler}. It does not validate that the node revisions actually exist. But when a node is deleted, the matching rows in {revisioning_scheduler} are not deleted.

This may break implementation of hook_node_update(), for instance of they use field_get_items() to retrieve a field value. In such as case, an exception could be thrown. This will strop the execution of revisioning_scheduler_cron() and prevent publication of the (valid) revisions scheduled after the one of a deleted node.

Proposed resolution

• In revisioning_scheduler_cron(), check the result of node_load($revision->revision_nid, $revision->revision_vid) before using it as argument of _revisioning_publish_revision()
• Implements hook_node_delete() to delete scheduled publications of deleted nodes' revisions.