Node clone: make cloning a node count as inserting a new translation instead of updating the original node's translation

Problem/Motivation

When cloning a node with the Node clone module (version 7.x-1.0) or importing a node with the Node export module (version 7.x-3.1), the new (cloned/imported) node contains much of the metadata from the previous node, including enough of the translation metadata for the entity_translation module to mistake the save operation for an update to the previous node's translation.

We do want to keep most of the original node's translation data; but we want the insert translation hooks to run, instead of the update hooks.

Among other things, this impacts the Search API Entity Translation module, which will only add nodes to the search index when entity_translation's insert hook (i.e.: hook_entity_translation_insert()) fires.

Proposed resolution

Implement hook_clone_node_alter() and explicitly set $node->translations->hook[$langcode]['hook'] = 'insert'; for each translation.

Remaining tasks

1. Write a patch
2. Review and feedback
3. RTBC and feedback
4. Commit

User interface changes

None.

API changes

None.

Data model changes

None.