Tasks introduced via 'sync' should trigger hooks

When using several instances of Taskwarrior on different devices (e.g. on a mobile phone with Android and on a computer), only locally added tasks trigger the on-modify hook.

Syncing means that tasks can be added from other sources and on-modify should be triggered when a new task comes in from a remote source. I see the exception made for sync to be counter-intuitive and cannot see a good reason for it.