node_publish trigger incompatible with programmatically-created nodes

The node_publish trigger, which by default is used to send notifications for new content, is only fired if a node is actually created via the web interface. If the node is instead created programmatically, e.g. by Feeds, then hook_exit() isn't called and thus neither is the node_publish trigger.

The end result is that notifications aren't sent for nodes created by Feeds or any module that depends on Feeds, such as Mailhandler.