portage.package.ebuild._config.UseManager.UseManager.getUseAliases(): Accept pkg argument of type str.
portage.dbapi.dbapi._match_use(): Use _emerge.Package.Package._iuse.get_real_flag().

It fixes support for USE aliases in:
  best_version
  has_version
  emerge --keep-going
  emerge --resume
cache/template.py: call self.sync() from __del__

This allows portdbapi.portdbapi_instances to be eliminated, which is
nice because we no longer has to be so careful to avoid memory leaks
involving this variable. It was not just annoying for portage
internals, but also for any API consumers that needed to create/destroy
many portdbapi instances.
_iter_match_use: construct _pkg_str instances

Now _match_use does not have to construct them itself.
porttree._dummy_list: fix infinite recursion
close_portdbapi_caches: portage.db atexit hook

The python interpreter does _not_ guarantee that destructors are
called for objects that remain when the interpreter exits, so we
use an atexit hook to call destructors for any global portdbapi
instances that may have been constructed.
emerge --metadata/regen: flush portdbapi cache
emerge_main: hold large objects in emerge_config

This allows emerge_main to avoid having direct local references to
large local objects (like "settings" and "trees"), making it easier to
ensure that stale objects can be garbage collected when other functions
refresh the config with calls to load_emerge_config(). This will be
much more flexible than the "gc_locals" approach that was introduce in
commit e9fd283aedf54e2effc73f4157524fe9a26993c0.
match_from_list: =* op with revision, bug #467826
emerge_main: call portdbapi destructors
man/portage.5: remove /etc/make.conf references

Since /etc/portage/make.conf supersedes /etc/make.conf, there's no need
to mention /etc/make.conf here anymore (it's still mentioned in
make.conf(5) though).
dep_check: remove redundant list copy

There's no need to copy the list before calling dep_wordreduce, since
dep_wordreduce copies the list internally.
_emerge_config: implement __iter__
_emerge_config: simplify __getitem__
man/make.conf.5: mention RSYNC_PROXY
emerge --autounmask-write: chk_updated_cfg_files

Instead of suggesting to call dispatch-conf, call chk_updated_cfg_files
in order to display a config update message when appropriate.
Show unevaluated atom in blocker parent display.
run_action: use emerge_config attrs, not locals
Show blocker parents for non slot-conflict pkgs.

Show parents for packages involved in blocker conflicts but not
directly involved in slot conflicts, since this information may be
helpful for troubleshooting blocker conflicts. This information had
been hidded when there were unrelated simultaneous slot conflicts,
since commit 77b651300731ec007cd535a83b8ee9a898602783.
action_build: remove useless --ask autoclean

This autoclean invocation would should have no effect anyway, unless
the vdb happens to be in an inconsistent state due to a previously
interrupted emerge (relatively rare).