gentoo: workaround python blocker

!!! Multiple package instances within a single package slot have been pulled
!!! into the dependency graph, resulting in a slot conflict

Bug: https://github.com/gentoo/gentoo-docker-images/issues/79
Close: #7

gentoo

@@ -5,12 +5,13 @@ COPY --from=portage /var/db/repos/gentoo /var/db/repos/gentoo
 
 ENV ACCEPT_KEYWORDS="amd64" \
     EMERGE_DEFAULT_OPTS="--jobs=9 --load-average=8 --with-bdeps=y" \
-    FEATURES="ccache -sandbox -usersandbox" \
+    FEATURES="ccache -sandbox -usersandbox -ipc-sandbox -network-sandbox -pid-sandbox" \
     CCACHE_SIZE="2G" \
     MAKEOPTS="-j9 -l8" \
     USE="cairo introspection jpeg tiff"
 
-RUN emerge dev-util/ccache \
+RUN emerge --unmerge dev-python/setuptools dev-python/certifi \
+&&  emerge dev-util/ccache dev-util/meson \
 &&  emerge app-text/poppler \
     dev-python/pycairo \
     dev-python/pygobject \