kig fails to build with gcc 10

[ 97%] Building CXX object CMakeFiles/kigpart.dir/scripting/python_scripter.cc.o
/usr/bin/c++  -DKCOREADDONS_LIB -DKIG_ENABLE_PYTHON_SCRIPTING -DLIB_PYTHON=\"libpython3.9.so.1.0\" -DQT_CONCURRENT_LIB -DQT_CORE_LIB -DQT_DBUS_LIB -DQT_GUI_LIB -DQT_NETWORK_LIB -DQT_NO_DEBUG -DQT_PRINTSUPPORT_LIB -DQT_SVG_LIB -DQT_USE_FAST_CONCATENATION -DQT_USE_FAST_OPERATOR_PLUS -DQT_WIDGETS_LIB -DQT_XMLPATTERNS_LIB -DQT_XML_LIB -DWITH_GEOGEBRA=1 -D_GNU_SOURCE -D_LARGEFILE64_SOURCE -Dkigpart_EXPORTS -I/builddir/build/BUILD/kig-19.12.1/x86_64-redhat-linux-gnu -I/builddir/build/BUILD/kig-19.12.1 -I/builddir/build/BUILD/kig-19.12.1/x86_64-redhat-linux-gnu/kigpart_autogen/include -I/builddir/build/BUILD/kig-19.12.1/modes -I/usr/include/python3.9 -I/usr/include/boost -isystem /usr/include/qt5 -isystem /usr/include/qt5/QtGui -isystem /usr/include/qt5/QtCore -isystem /usr/lib64/qt5/mkspecs/linux-g++ -isystem /usr/include/qt5/QtSvg -isystem /usr/include/qt5/QtWidgets -isystem /usr/include/qt5/QtPrintSupport -isystem /usr/include/KF5/KCrash -isystem /usr/include/KF5 -isystem /usr/include/KF5/KParts -isystem /usr/include/KF5/KIOWidgets -isystem /usr/include/KF5/KIOCore -isystem /usr/include/KF5/KCoreAddons -isystem /usr/include/KF5/KService -isystem /usr/include/KF5/KConfigCore -isystem /usr/include/qt5/QtNetwork -isystem /usr/include/qt5/QtConcurrent -isystem /usr/include/qt5/QtDBus -isystem /usr/include/KF5/KJobWidgets -isystem /usr/include/KF5/KCompletion -isystem /usr/include/KF5/KWidgetsAddons -isystem /usr/include/KF5/KXmlGui -isystem /usr/include/qt5/QtXml -isystem /usr/include/KF5/KConfigWidgets -isystem /usr/include/KF5/KCodecs -isystem /usr/include/KF5/KConfigGui -isystem /usr/include/KF5/KAuth -isystem /usr/include/KF5/KTextWidgets -isystem /usr/include/KF5/SonnetUi -isystem /usr/include/KF5/KI18n -isystem /usr/include/KF5/KTextEditor -isystem /usr/include/KF5/KIconThemes -isystem /usr/include/KF5/KArchive -isystem /usr/include/qt5/QtXmlPatterns  -O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS -fexceptions -fstack-protector-strong -grecord-gcc-switches -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -mtune=generic -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection -fno-operator-names -Wall -Wextra -Wcast-align -Wchar-subscripts -Wformat-security -Wno-long-long -Wpointer-arith -Wundef -Wnon-virtual-dtor -Woverloaded-virtual -Werror=return-type -Wvla -Wdate-time -Wsuggest-override -Wlogical-op -std=c++11 -fexceptions -DNDEBUG -fPIC -fvisibility=hidden -fvisibility-inlines-hidden   -fPIC -std=gnu++11 -fexceptions -o CMakeFiles/kigpart.dir/scripting/python_scripter.cc.o -c /builddir/build/BUILD/kig-19.12.1/scripting/python_scripter.cc
make[2]: Leaving directory '/builddir/build/BUILD/kig-19.12.1/x86_64-redhat-linux-gnu'
*** WARNING *** there are active plugins, do not report this as a bug unless you can reproduce it without enabling any plugins.
Event                            | Plugins
PLUGIN_FINISH_UNIT               | annobin: Generate final annotations
PLUGIN_START_UNIT                | annobin: Generate global annotations
PLUGIN_ALL_PASSES_START          | annobin: Generate per-function annotations
PLUGIN_ALL_PASSES_END            | annobin: Register per-function end symbol
In file included from /usr/include/boost/python.hpp:55,
                 from /builddir/build/BUILD/kig-19.12.1/scripting/python_scripter.cc:31:
/usr/include/boost/python/raw_function.hpp: In member function 'PyObject* boost::python::detail::raw_dispatcher<F>::operator()(PyObject*, PyObject*)':
/usr/include/boost/python/raw_function.hpp:33:76: internal compiler error: in nothrow_spec_p, at cp/except.c:1247
   33 |                     , keywords ? dict(borrowed_reference(keywords)) : dict()
      |   

This failure happened during our Python 3.9 rebuilds. While not related to Python 3.9, it still blocks it.

For the build logs, see:
https://copr-be.cloud.fedoraproject.org/results/@python/python3.9/fedora-rawhide-x86_64/01173445-kig/

For all our attempts to build kig with Python 3.9, see:
https://copr.fedorainfracloud.org/coprs/g/python/python3.9/package/kig/