drush features-revert throws undefined function error

Issue Summary

Related to the work done in #1840236: hook_feature_revert() incorrect?.

I have created a features module drupal7_metatag with some metatag configs

When I revert the feature with metatag configs with drush fr --force drupal7_metatag I am getting the following error

The issue is drupal7_metatag.features.metatag.inc is not being loaded before the function drupal7_metatag_metatag_export_default() is called in metatag_feature_revert(). I have confirmed that by adding a include_once 'drupal7_metatag.features.metatag.inc'; in the drupal7_metatag.module solves the problem. With a lot of help from q0rban and juampy, we noticed that features_include_defaults() is not getting loaded to include all the necessary inc files. Looking through the implementation of features.taxonomy, features.user, etc, it seems like the standard way to implement a hook_features_revert() is to call features_get_default('{module}', $module). Patch to follow.