* Dependencies can be satisfied by installed packages that do not have matching
ebuilds in the portage tree or overlay.
* Emerge automatically ignores blockers that are made irrelevant by an upgrade.
+* Emerge supports "reverse blocker detection" which means that the blockers of
+ installed packages will always be respected.
* Emerge builds a complete dependency graph in order to ensure correct merge
order and detection of circular dependencies.
* The world and system sets allow automatic update of all installed slots.
portage-2.1.2
==================================
+* Depending on the number of packages installed, users may notice a difference
+ in the time taken for dependency calculations. This performance penalty is
+ due to the addition of important new features which include the ability to
+ detect reverse blockers, the building of a complete dependency graph, and the
+ ability to use installed packages to satisify dependencies even after their
+ ebuilds have been removed from the portage tree.
* emerge does not necessarily update build time dependencies that are not
strictly required. See the --with-bdeps option in the emerge(1) man page.