Merging just the title (prefix) field doesn't update the record properly

Create two contacts that will match as duplicates (but make sure one has a different title/prefix)

Merge the two contacts taking only the different title across.

View the result..

The title appears to have changed when viewing the record as the display name has been updated but the prefix_id field hasn't been updated. You can tell my clicking to edit the contacts name as the old title will be selected in the prefix drop down.

The pre and post hooks also get the wrong prefix information as well.

If you also update the contacts name at the same time as the title/prefix then it all works OK.

Not tested yet but this will likely affect suffix field as well.
Not tested yet but may affect other fields if only merging one field.

The issue is marked as major as it is data loss and the bug hides that fact from the user so it is not easy to catch.
The issue may relate to CRM-14312.