Regression in features_flush_caches()

This one's my fault :)
#1530386: Avoid unnecessary cache rebuilds and improve installation performance introduced the logic in features_flush_caches() that doesn't flush the modules cache during install.
At least that was the intention, it is actually backwards.
See:

  // Don't flush the modules cache during installation, for performance reasons
  if (variable_get('install_task') != 'done') {
    features_get_modules(NULL, TRUE);
  }