python2 issues

[zx2c4]

The trend is for python packages to drop support of python2_7. That will help fix the below.

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

Calculating dependencies... done!
[ebuild     UD ] dev-python/numpy-1.16.5::gentoo [1.17.4-r2::gentoo] USE="lapack -doc -test" PYTHON_TARGETS="python2_7%* python3_6 -python3_7 (-python3_8%)" 0 KiB
[ebuild     UD ] dev-python/cairocffi-0.9.0-r1::gentoo [1.1.0::gentoo] USE="-doc -test" PYTHON_TARGETS="python2_7%* python3_6 -python3_7 (-python3_8%)" 0 KiB
[ebuild     UD ] dev-python/matplotlib-2.2.4::gentoo [3.1.2::gentoo] USE="cairo qt5 (-doc) -examples -excel -gtk2% -gtk3 -latex -test -tk -wxwidgets" PYTHON_TARGETS="python2_7%* python3_6 -python3_7" 0 KiB
[ebuild  N     ] sci-mathematics/gap-4.10.2-r1:0/4.10.2::sage-on-gentoo  USE="readline recommended_pkgs vim-syntax -emacs" 0 KiB
[ebuild     UD ] dev-python/sphinx-1.8.5-r1::sage-on-gentoo [2.0.1::gentoo] USE="-doc -latex -net% -test" PYTHON_TARGETS="python2_7%* python3_6 -pypy3 -python3_7 (-python3_8%)" 0 KiB
[ebuild  N     ] sci-mathematics/sage-9.0::sage-on-gentoo  USE="X doc-html-bin -bliss -debug -doc-html -doc-pdf -doc-pdf-bin -jmol -latex -testsuite" L10N="en -ca -de -es -fr -hu -it -ja -pt -ru -tr" PYTHON_TARGETS="python3_6 -python3_7" 0 KiB
[blocks B      ] <dev-python/numpy-1.17 ("<dev-python/numpy-1.17" is blocking dev-python/numpy-python2-1.16.5)

Total: 6 packages (4 downgrades, 2 new), Size of downloads: 0 KiB
Conflict: 1 block (1 unsatisfied)

 * Error: The above package list contains packages which cannot be
 * installed at the same time on the same system.

  (dev-python/numpy-1.16.5:0/0::gentoo, ebuild scheduled for merge) pulled in by
    dev-python/numpy[python_targets_python3_6(-)?,python_targets_python3_7(-)?,-python_single_target_pypy3(-),-python_single_target_python2_7(-),-python_single_target_python3_8(-),python_single_target_python3_6(+)?,python_single_target_python3_7(+)?] (dev-python/numpy[python_targets_python3_6(-),-python_single_target_pypy3(-),-python_single_target_python2_7(-),-python_single_target_python3_8(-),python_single_target_python3_6(+)]) required by (media-gfx/inkscape-1.0_beta2:0/0::gentoo, installed) USE="cdr dbus exif jpeg lcms nls openmp spell -dia -graphicsmagick -imagemagick -inkjar -jemalloc -postscript -static-libs -svg2 -visio -wpg" ABI_X86="(64)" PYTHON_SINGLE_TARGET="python3_6 -python3_7" PYTHON_TARGETS="python3_6 -python3_7"
    >=dev-python/numpy-1.16.1[python_targets_python3_6(-)?,python_targets_python3_7(-)?,-python_single_target_python3_6(-),-python_single_target_python3_7(-)] (>=dev-python/numpy-1.16.1[python_targets_python3_6(-),-python_single_target_python3_6(-),-python_single_target_python3_7(-)]) required by (sci-mathematics/sage-9.0:0/0::sage-on-gentoo, ebuild scheduled for merge) USE="X doc-html-bin -bliss -debug -doc-html -doc-pdf -doc-pdf-bin -jmol -latex -testsuite" ABI_X86="(64)" L10N="en -ca -de -es -fr -hu -it -ja -pt -ru -tr" PYTHON_TARGETS="python3_6 -python3_7"
    dev-python/numpy[python_targets_python3_6(-)?,python_targets_python3_7(-)?,-python_single_target_python3_6(-),-python_single_target_python3_7(-)] (dev-python/numpy[python_targets_python3_6(-),-python_single_target_python3_6(-),-python_single_target_python3_7(-)]) required by (dev-python/fpylll-0.5.1:0/0::sage-on-gentoo, installed) USE="-test" ABI_X86="(64)" PYTHON_TARGETS="python3_6 -python3_7"
    >=dev-python/numpy-1.6[python_targets_python2_7(-)?,python_targets_python3_6(-)?,python_targets_python3_7(-)?,-python_single_target_python2_7(-),-python_single_target_python3_6(-),-python_single_target_python3_7(-)] (>=dev-python/numpy-1.6[python_targets_python3_6(-),-python_single_target_python2_7(-),-python_single_target_python3_6(-),-python_single_target_python3_7(-)]) required by (dev-python/numexpr-2.6.9:0/0::gentoo, installed) USE="-mkl" ABI_X86="(64)" PYTHON_TARGETS="python3_6 -python2_7 -python3_7"
    >=dev-python/numpy-1.9.1[python_targets_python3_6(-)?,python_targets_python3_7(-)?,-python_single_target_python3_6(-),-python_single_target_python3_7(-)] (>=dev-python/numpy-1.9.1[python_targets_python3_6(-),-python_single_target_python3_6(-),-python_single_target_python3_7(-)]) required by (dev-python/bottleneck-1.2.1-r1:0/0::gentoo, installed) USE="-test" ABI_X86="(64)" PYTHON_TARGETS="python3_6 -python3_7"
    >dev-python/numpy-1.13.1[python_targets_python3_6(-)?,python_targets_python3_7(-)?,-python_single_target_python3_6(-),-python_single_target_python3_7(-)] (>dev-python/numpy-1.13.1[python_targets_python3_6(-),-python_single_target_python3_6(-),-python_single_target_python3_7(-)]) required by (dev-python/pandas-0.24.2:0/0::gentoo, installed) USE="X (-doc) -full-support -minimal -test" ABI_X86="(64)" PYTHON_TARGETS="python3_6 -python3_7"
    >=dev-python/numpy-1.7.1[python_targets_python2_7(-)?,python_targets_python3_6(-)?,python_targets_python3_7(-)?,-python_single_target_python2_7(-),-python_single_target_python3_6(-),-python_single_target_python3_7(-)] (>=dev-python/numpy-1.7.1[python_targets_python2_7(-),python_targets_python3_6(-),-python_single_target_python2_7(-),-python_single_target_python3_6(-),-python_single_target_python3_7(-)]) required by (dev-python/matplotlib-2.2.4:0/0::gentoo, ebuild scheduled for merge) USE="cairo qt5 (-doc) -examples -excel -gtk2 -gtk3 -latex -test -tk -wxwidgets" ABI_X86="(64)" PYTHON_TARGETS="python2_7 python3_6 -python3_7"
    dev-python/numpy[python_targets_python3_6(-)?,python_targets_python3_7(-)?,-python_single_target_python3_6(-),-python_single_target_python3_7(-)] (dev-python/numpy[python_targets_python3_6(-),-python_single_target_python3_6(-),-python_single_target_python3_7(-)]) required by (dev-python/rpy-2.9.0:0/0::gentoo, installed) USE="-test" ABI_X86="(64)" PYTHON_TARGETS="python3_6 -python3_7"
    >=dev-python/numpy-1.10[lapack,python_targets_python3_6(-)?,python_targets_python3_7(-)?,python_targets_python3_8(-)?,-python_single_target_python3_6(-),-python_single_target_python3_7(-),-python_single_target_python3_8(-)] (>=dev-python/numpy-1.10[lapack,python_targets_python3_6(-),-python_single_target_python3_6(-),-python_single_target_python3_7(-),-python_single_target_python3_8(-)]) required by (sci-libs/scipy-1.4.1:0/0::gentoo, installed) USE="-doc -sparse -test" ABI_X86="(64)" PYTHON_TARGETS="python3_6 -python3_7 -python3_8"

  (dev-python/numpy-python2-1.16.5:0/0::gentoo, installed) pulled in by
    >=dev-python/numpy-python2-1.16.5[python_targets_python2_7(-)?,-python_single_target_python2_7(-)] (>=dev-python/numpy-python2-1.16.5[python_targets_python2_7(-),-python_single_target_python2_7(-)]) required by (dev-python/pygtk-2.24.0-r4:2/2::gentoo, installed) USE="-doc -examples -test" ABI_X86="(64)" PYTHON_TARGETS="python2_7"

For more information about Blocked Packages, please refer to the following
section of the Gentoo Linux x86 Handbook (architecture is irrelevant):

https://wiki.gentoo.org/wiki/Handbook:X86/Working/Portage#Blocked_packages

[kiwifb]

I can remove py2 support from the few packages that still have it in the overlay. The only one with that issue in the list above is sphinx. But I have a feeling it is matplotlib that gives you trouble.

[kiwifb]

python2 has now been removed from all the ebuilds in dev-python from the overlay. Only two usage remain. scipy-1.2.1 and singular (for which it is an optional dep not needed for sage). Using scipy 1.4 with sage should be tested. If it works reasonably well, scipy can be (once again) removed from the overlay.

[kiwifb]

Hum... Making sphinx 1.8.5-r1 py3 only means I had to introduce a package.use -python_targets_python2_7 for sphinxcontrib-websupport. If you still have python2_7 in your PYTHON_TARGETS, this is definitely an issue.

[kiwifb]

Using scipy 1.4 leads to some warnings which breaks doctesting. There is a patch taking care of most of them. But some remain as they are caused indirectly by networkx. This is fixed in upstream networkx but not in a release. My understanding is that backporting to networkx-2.4 would be a patch bomb.

[kiwifb]

Obsolete now.