How can I programmatically set the default export path? In Drupal 7, you can set the default export path for the features module by setting the variable 'features_default_export_path':

variable_set('features_default_export_path', 'sites/all/modules/custom/features');


What is the equivalent in Drupal 8? Can the export path be set in the features.settings configuration object?
It looks like configuration for the features module is managed in the features.settings configuration object. This settings can be viewed and change via drush.

Viewing the features configuration directory:

drush cget features.settings


Setting the features configuration directory: 

drush cset features.settings export.folder "custom/features"