Is it safe to delete 'sites/modules.sav'? After the upgrade to the newest Drupal v7.31 I've found a new directory called sites/modules.sav with some subdirectories like


entity
entityreference
securelogin
securepages
session443


What is the purpose of this directory?

Can I safely delete this entire directory 'modules.sav' after the successful upgrade?
Yes, as far as Drupal is concerned, it's safe to delete that folder. Whether it's needed for something outside of Drupal I obviously couldn't say.

Drupal didn't put it there, and unless you've got a very abnormal setup (which you'd undoubtedly know about already), it's not going to be looking in that folder for any files.

It's probably a remnant of whatever automated method you used to update Drupal; if you'd done the upgrade manually that folder wouldn't have appeared.

To be sure, take a full backup, remove the folder on a dev version of the site, and run the usual tests you would after a normal upgrade. If those all pass, you'll know 100%.