_dep_check_composite_db: fix bug #526160

The fixes various forms of buggy behavior involving virtuals handling
and EAPI 5 subslots. The code at fault is part of the support for
bug #141118 (virtuals lookahead). This code was written long before
subslots existed, and because of them it needs to be updated now.

Previously, the relevant virtuals code would only select one virtual
from each slot for lookahead. Now, it needs to select one from each
slot/subslot pair. The buggy forms of behavior fixed by this change
can be difficult to reproduce, since they only express themselves
under some rare circumstances.

In addition to the _dep_check_composite_db fixes, there is also a
related fix inside _expand_new_virtuals, which is required so that
_slot_operator_update_probe can reliably check whether or not a
particular input atom was selected. Without this change, the
_dep_check_composite_db changes will cause the test from commit
d3be49fe6827aa1974856dffe6d5a1aca80a7bed to fail in a way that is
very similar to the failure reported in bug #526160.

Fixes: d3be49fe6827 ("depgraph: fix bug #526160")
X-Gentoo-Bug: 526160
X-Gentoo-Bug-URL: https://bugs.gentoo.org/show_bug.cgi?id=526160
Acked-by: Brian Dolbec <dolsen@gentoo.org>
LocationsManager: enable user package.bashrc

In /etc/portage/profile, we already have support for using directories
in the place of regular config files (portage1_directories = True). So,
go ahead and enable package.bashrc there too.

We could also support /etc/portage/package.bashrc, but that would be
more complicated since /etc/portage/bashrc is the long-standing location
of the user's bashrc which applies to all packages, and package.bashrc
would instead expect /etc/portage/bashrc to be a directory containing
per-package bashrc files. So for now, we only support package.bashrc
inside /etc/portage/profile.

Note that since /etc/portage/profile is not part of a repository,
there's no associated layout.conf. So, there's no way to enable the
profile-env profile-formats setting in /etc/portage/profile, except by
hardcoding.

Signed-off-by: Zac Medico <zmedico@gentoo.org>
Acked-by: Brian Dolbec <dolsen@gentoo.org>
If a binhost file sets a TTL header, honor it.

Reviewed-on: https://chromium-review.googlesource.com/225279
Reviewed-on: https://chromium-review.googlesource.com/225423
Tested-by: David James <davidjames@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Zac Medico <zmedico@gentoo.org>
Acked-by: Brian Dolbec <dolsen@gentoo.org>
etc-update: symlink support for bug #485598

This includes numerous logic adjustments that are needed to support
protected symlinks. The show_diff function now supports arbitrary
file types. For example, a diff between two symlinks looks like this:

-SYM: /foo/bar -> baz
+SYM: /foo/bar -> blah

X-Gentoo-Bug: 485598
X-Gentoo-Bug-URL: https://bugs.gentoo.org/show_bug.cgi?id=485598
dispatch-conf: symlink support for bug #485598

This includes numerous logic adjustments that are needed to support
protected symlinks. The new diff_mixed function is used for diffs
between arbitrary file types. For example, a diff between two symlinks
looks like this:

-SYM: /foo/bar -> baz
+SYM: /foo/bar -> blah

X-Gentoo-Bug: 485598
X-Gentoo-Bug-URL: https://bugs.gentoo.org/show_bug.cgi?id=485598
CONFIG_PROTECT: protect symlinks, bug #485598

Users may not want some symlinks to get clobbered, so protect them
with CONFIG_PROTECT. Changes were required in the dblink.mergeme method
and the new_protect_filename function.

The changes to dblink.mergeme do 3 things:

 * Move the bulk of config protection logic from dblink.mergeme to a
   new dblink._protect method. The new method only returns 3 variables,
   which makes it easier to understand how config protection interacts
   with the dblink.mergeme code that uses those variables. This is
   important, since dblink.mergeme has so many variables.

 * Initialize more variables at the beginning of dblink.mergeme, since
   those variables are used by the dblink._protect method.

 * Use the variables returned from dblink._protect to trigger
   appropriate behavior later in dblink.mergeme.

The new_protect_filename changes are required since this function
compares the new file to old ._cfg* files that may already exist, in
order to avoid creating duplicate ._cfg* files. In these comparisons,
it needs to handle symlinks differently from regular files.

The unit tests demonstrate operation in many different scenarios,
including:

 * regular file replaces regular file
 * regular file replaces symlink
 * regular file replaces directory
 * symlink replaces symlink
 * symlink replaces regular file
 * symlink replaces directory
 * directory replaces regular file
 * directory replaces symlink

X-Gentoo-Bug: 485598
X-Gentoo-Bug-URL: https://bugs.gentoo.org/show_bug.cgi?id=485598
Remove redundant PORTAGE_XATTR_EXCLUDE defaults (527636)

In install.py and movefile.py there were some redundant default
PORTAGE_XATTR_EXCLUDE settings. The default settings in make.globals
should be sufficient. Therefore, remove the redundant settings so that
we don't have to maintain them.

Fixes: 2fcdb5f36fac ("Add btrfs.* to default PORTAGE_XATTR_EXCLUDE (527636)")
X-Gentoo-Bug: 527636
X-Gentoo-Bug-URL: https://bugs.gentoo.org/show_bug.cgi?id=527636
Acked-by: Brian Dolbec <dolsen@gentoo.org>
Acked-by: Anthony G. Basile <blueness@gentoo.org>