At first I was unable to emerge a package:

emerge --ask anki                    
 
These are the packages that would be merged, in order:
 
Calculating dependencies... done!
 
emerge: there are no ebuilds built with USE flags to satisfy "dev-python/markdown[python_targets_python3_6(-)?,-python_single_target_jython2_7(-),-python_single_target_pypy(-),-python_single_target_pypy3(-),-python_single_target_python2_7(-),-python_single_target_python3_4(-),-python_single_target_python3_5(-),python_single_target_python3_6(+)]".
!!! One of the following packages is required to complete your request:

• app-misc/anki-2.1.0_beta27::nokit (Change USE: -python_targets_python3_6, this change violates use flag constraints defined by app-misc/anki-2.1.0_beta27: 'python_targets_python3_6')
  (dependency required by "app-misc/anki-2.1.0_beta27::nokit" [ebuild])
  (dependency required by "anki" [argument])
   
   
  USE="-python_targets_python3_6" emerge --ask anki
   
  These are the packages that would be merged, in order:
   
  Calculating dependencies \
   
  !!! Problem resolving dependencies for app-misc/anki                                                                                                ... done!
   
  !!! The ebuild selected to satisfy "anki" has unmet requirements.
• app-misc/anki-2.1.0_beta27::nokit USE="recording sound -latex -test" PYTHON_TARGETS="-python3_6"
   
    The following REQUIRED_USE flag constraints are unsatisfied:
      python_targets_python3_6

  I added "python-kit = 3.6-prime" to /etc/ego.conf , ego sync, and then emerge -uvUND @world

  It then emerged successfully:

build.log:

• Package: app-misc/anki-2.1.0_beta27
• Repository: nokit
• Maintainer: patrick@gentoo.org
• USE: amd64 elibc_glibc kernel_linux python_targets_python3_6 recording sound userland_GNU
• FEATURES: keeptemp preserve-libs sandbox userpriv usersandbox
  >>> Unpacking source...
  >>> Unpacking anki-2.1.0_beta27.tgz to /var/tmp/portage/app-misc/anki-2.1.0_beta27/work
  >>> Source unpacked in /var/tmp/portage/app-misc/anki-2.1.0_beta27/work
  >>> Preparing source in /var/tmp/portage/app-misc/anki-2.1.0_beta27/work/anki-2.1.0beta27 ...
• Applying anki-2.1.0_beta25-web-folder.patch ... [ ok ]
  >>> Source prepared.
  >>> Configuring source in /var/tmp/portage/app-misc/anki-2.1.0_beta27/work/anki-2.1.0beta27 ...
  >>> Source configured.
  >>> Compiling source in /var/tmp/portage/app-misc/anki-2.1.0_beta27/work/anki-2.1.0beta27 ...
  >>> Source compiled.
  >>> Test phase [not enabled]: app-misc/anki-2.1.0_beta27

>>> Install anki-2.1.0_beta27 into /var/tmp/portage/app-misc/anki-2.1.0_beta27/image/ category app-misc
>>> Completed installing anki-2.1.0_beta27 into /var/tmp/portage/app-misc/anki-2.1.0_beta27/image/

• Final size of build directory: 15520 KiB (15.1 MiB)
• Final size of installed tree: 17472 KiB (17.0 MiB)

ecompressdir: bzip2 -9 //usr/share/man
ecompressdir: bzip2 -9 //usr/share/doc

• Updating .desktop files database ... [ ok ]
• Updating .desktop files database ... [ ok ]

  But when I tried to run the program it fails with:

nyquistfreq$ anki
Traceback (most recent call last):
File "/usr/lib/python-exec/python3.6/anki", line 6, in <module>
import aqt
File "/usr/lib64/python3.6/site-packages/aqt/_init_.py", line 14, in <module>
from aqt.qt import *
File "/usr/lib64/python3.6/site-packages/aqt/qt.py", line 17, in <module>
from PyQt5.QtWebEngineWidgets import QWebEnginePage
RuntimeError: PyQt5.QtWebEngineWidgets cannot import type '����' from PyQt5.QtCore

 

emerge -pv anki

These are the packages that would be merged, in order:

Calculating dependencies... done!
[ebuild R ] app-misc/anki-2.1.0_beta27::nokit USE="recording sound -latex {-test}" PYTHON_TARGETS="python3_6" 0 KiB

Total: 1 package (1 reinstall), Size of downloads: 0 KiB

Then I used this script: https://github.com/bradlyatc/scripts/blob/master/pyslotrbd

to rebuild all the packages depending on python: emerge -1v $(python3 ./pyslotrbd)

app-admin/ego:0
app-misc/anki:0
app-portage/gentoolkit:0
dev-lang/python-exec:2
dev-lang/yasm:0
dev-libs/boost:0
dev-libs/glib:2
dev-libs/libxml2:2
dev-libs/libxslt:0
dev-python/PyQt5:0
dev-python/PySocks:0
dev-python/appi:0
dev-python/asn1crypto:0
dev-python/beautifulsoup:4
dev-python/certifi:0
dev-python/cffi:0
dev-python/chardet:0
dev-python/cryptography:0
dev-python/cython:0
dev-python/dbus-python:0
dev-python/decorator:0
dev-python/enum34:0
dev-python/html5lib:0
dev-python/httplib2:0
dev-python/idna:0
dev-python/ipaddress:0
dev-python/lxml:0
dev-python/markdown:0
dev-python/mwparserfromhell:0
dev-python/numpy:0
dev-python/ply:0
dev-python/pyaudio:0
dev-python/pycparser:0
dev-python/pyelftools:0
dev-python/pyopenssl:0
dev-python/pyxattr:0
dev-python/requests:0
dev-python/send2trash:0
dev-python/setuptools:0
dev-python/sip:0
dev-python/six:0
dev-python/urllib3:0
dev-python/webencodings:0
dev-util/boost-build:0
dev-util/gdbus-codegen:0
dev-util/meson:0
dev-util/scons:0
dev-vcs/git:0
media-libs/alsa-lib:0
media-libs/libcaca:0
media-libs/opencv:0
sys-apps/file:0
sys-apps/kmod:0
sys-apps/portage:0
sys-apps/usbutils:0
sys-apps/util-linux:0
sys-boot/boot-update:0
sys-devel/clang:5
sys-devel/clang:6
sys-fs/cryptsetup:0
sys-libs/cracklib:0
virtual/python-ipaddress:0
x11-proto/xcb-proto:0

but the program still fails to run.

 

other info:

nyquistfreq$ ego kit

ego kit
/var/git/meta-repo (updated 3 hours 13 minutes ago):

kit active branch default stability
core-kit 1.0-prime (same) prime
core-hw-kit master (same) prime
security-kit 1.0-prime (same) prime
xorg-kit 1.19-prime (same) prime
gnome-kit 3.20-prime (same) prime
kde-kit 5.12-prime (same) prime
media-kit 1.1-prime (same) prime
perl-kit 5.24-prime (same) prime
python-kit 3.6-prime 3.4-prime prime
php-kit master (same) prime
java-kit 1.1-prime (same) prime
ruby-kit 1.1-prime (same) prime
haskell-kit 1.1-prime (same) prime
ml-lang-kit 1.2-prime (same) prime
lisp-scheme-kit 1.1-prime (same) prime
lang-kit 1.1-prime (same) prime
llvm-kit 1.2-prime (same) prime
dev-kit 1.1-prime (same) prime
xfce-kit 4.12-prime (same) prime
desktop-kit 1.1-prime (same) prime
editors-kit master (same) prime
net-kit master (same) prime
text-kit master (same) prime
science-kit master (same) prime
games-kit master (same) prime
nokit master (same) prime

NOTE: This information comes from /etc/ego.conf and meta-repo metadata. After making changes to ego.conf, be sure to run ego sync in so
that the individual kit repositories on disk are synchronized with the kit branches shown above.