function onEntries( error, pkgs ) {
		if ( error ) {
			debug( 'Encountered an error when determining entry points: %s', error.message );
			return cb( error );
		}
		debug( 'Successfully determined entry points.' );
		cb( null, pkgs );
	}
Callback invoked upon determining entry points.

@private
@param {(Error|null)} error - error object
@param {ObjectArray} pkgs - packages
@returns {void}