Raise PluginConflictException instead of the generic Exception for new hook.
Raise PluginConflictException instead of the generic Exception for new hook.

beetbox/beets,ibmibmibm/beets,beetbox/beets,ibmibmibm/beets,beetbox/beets,ibmibmibm/beets,ibmibmibm/beets,beetbox/beets