Bug#972916: sagemath ftbfs with python3.9

[Matthias Klose]

Package: src:sagemath
Version: 9.2~beta12-1
Severity: serious
Tags: sid bullseye ftbfs
User: debian-python at lists.debian.org
Usertags: python3.9

sagemath ftbfs with python3.9; to reproduce, you can use the repositories found at:

deb [trusted=yes] http://people.debian.org/~doko/tmp/python3.9 ./
deb [trusted=yes] http://people.debian.org/~ginggs/python3.9-repo ./

see
https://people.debian.org/~ginggs/python3.9-default/sagemath_9.2~beta12-1build1_amd64-2020-10-23T22:48:30Z.build

[...]
make --no-print-directory all-sage
make --no-print-directory sage_conf-no-deps
cd '/<<PKGBUILDDIR>>/sage/build/pkgs/sage_conf' && .
'/<<PKGBUILDDIR>>/sage/src/bin/sage-env-config' && .
'/<<PKGBUILDDIR>>/sage/src/bin/sage-env' && .
'/<<PKGBUILDDIR>>/sage/build/bin/sage-build-env-config' && sage-logger -p
'/<<PKGBUILDDIR>>/sage/build/pkgs/sage_conf/spkg-install'
'/<<PKGBUILDDIR>>/sage/logs/pkgs/sage_conf-none.log'
[sage_conf-none] Installing
[sage_conf-none] Error: Tried to use Sage's Python which was not yet installed.
[sage_conf-none] If this was called from an spkg-install script for another
[sage_conf-none] package you should add $(PYTHON) as a dependency in
[sage_conf-none] build/pkgs/<pkg>/dependencies
[sage_conf-none] Error: could not determine package name
[sage_conf-none]
********************************************************************************
[sage_conf-none] Error installing
[sage_conf-none]
********************************************************************************
make[8]: *** [Makefile:2161: sage_conf-no-deps] Error 1
make[7]: *** [Makefile:2161:
/<<PKGBUILDDIR>>/sage/local/var/lib/sage/installed/sage_conf-none] Error 2
make[6]: *** [Makefile:1769: all-build] Error 2