Fatal Error: Call to undefined function in a drush backup module I am getting a weird error when attempting to use Drush.


  Fatal error: Call to undefined function variable_get() in
  /home/1000/.drush/backups/pantheon/20161102190143/modules/xmlsitemap/xmlsitemap.drush.inc on line 29
  Drush command terminated abnormally due to an unrecoverable error.
  Error: Call to undefined function variable_get() in /home/1000/.drush/backups/pantheon/20161102190143/modules/xmlsitemap/xmlsitemap.drush.inc, line 29


I have disabled and removed the xmlsitemap module, but it looks like it is referencing some weird backup version of the module.
The function variable_get doesn't exist in Drupal 8. I suggest just removing ~/.drush/backups/pantheon/20161102190143/modules/xmlsitemap/xmlsitemap.drush.inc or moving ~/.drush/backups to ~/.drushbackups if you can control this. 

Your problem is probably caused by the fact that you are putting the backup inside the ~/.drush directory and Drush is parsing code/files in that directory.