Fix crash in depgraph._remove_pkg

Make sure we don't try to remove a packages twice. This happened in the
past when a package was its own digraph-child.

One way to trigger this is a DEPEND on itself as in the test case.

This bug was reported by slyfox on IRC. In his case the cause for the
self-edge is unknown. Unfortunately the system state is lost.
Always warn about unknown mirrors (bug 501352)
Remove bogus countdown during clean list printing (bug 501296)

Before this patch a fake unmerge countdown would be shown
after an @system package was printed. If the users aborts
at this point, it looked as if some packages were missing
from the clean list compared to the --pretend output.
Implement --newrepo flag.

The --newrepo flag tells emerge to recompile a package if it is now
being pulled from a different repository.

BUG=chromium:200417
TEST=Verify ebuilds get pulled in when repo changes.
TEST=New test cases.
Change-Id: I8d5ff1cfc8c1d23e00c733b861547d3626bc2ece
Use function pointer when choosing qa output function

Replace the chain of if/else statements deciding which output formatting
function to use with a function pointer wrt comments by vapier
README: Cap at 72 columns
slot collision output: fix indent
Handle bad PORTAGE_BINHOST gracefully (bug 502288)
DEVELOPING: Mention that tab stop should be 4
Clean up bad PORTAGE_BINHOST handling

Suggested-by: Arfrever Frehtes Taifersar Arahesis <Arfrever@Apache.Org>
Reviewed-by: Arfrever Frehtes Taifersar Arahesis <Arfrever@Apache.Org>
Add a test case for --newuse, --changed-use, and --binpkg-respect-use.

Change-Id: I201e468c6e7cda6aa961371ad9ddc10cfab04bc7
Update dates in recently changed files.
ebuild-helpers/xattr/install: use the binary wrapper if available; fall back to the python one

Signed-off-by: Gregory M. Turner <gmt@be-evil.net>
xattr/install helper: put /usr/bin at front of path to avoid invocation-bomb

Signed-off-by: Gregory M. Turner <gmt@be-evil.net>