/var/lib/portage/world, has been extended to include nested sets that may
be listed /var/lib/portage/world_sets.
+portage-2.1.11
+==================================
+* User-defined package sets can now be created by placing files in the
+ /etc/portage/sets/ directory. Refer to the emerge(1) and portage(5) man
+ pages for more information.
+
portage-2.1.10.61
==================================
* FEATURES=config-protect-if-modified is now enabled by default. This causes