Comment 1 for bug 1784348

Confirmed these are no longer built in debian:

$ rmadison -S flint-arb -s unstable -u debian
flint-arb | 2.11.1-2 | unstable | source
flint-arb | 1:2.12.0-3 | unstable | source
libflint-arb-dev | 2.11.1-2+b1 | unstable | armel, armhf
libflint-arb-dev | 1:2.12.0-3 | unstable | amd64, arm64, hurd-i386, i386, kfreebsd-amd64, kfreebsd-i386, mips, mips64el, mipsel, ppc64el, s390x
libflint-arb-doc | 2.11.1-2 | unstable | all
libflint-arb-doc | 1:2.12.0-3 | unstable | all
libflint-arb2 | 2.11.1-2+b1 | unstable | armel, armhf
libflint-arb2 | 1:2.12.0-3 | unstable | amd64, arm64, hurd-i386, i386, kfreebsd-amd64, kfreebsd-i386, mips, mips64el, mipsel, ppc64el, s390x

$ rmadison -S sagemath -s unstable -u debian
sagemath | 8.1-7 | unstable | source, armhf
sagemath | 8.2-4 | unstable | source, arm64, mipsel
sagemath | 8.2-5 | unstable | source, amd64, i386, mips64el, ppc64el
sagemath-common | 8.1-7 | unstable | all
[...]

All of the reverse-depends are either from these packages themselves, or from an arch:all reference:

(AA)apw@brain:~/Downloads/X/boot$ reverse-depends src:flint-arb
Reverse-Recommends
==================
* science-mathematics-dev (for libflint-arb-dev)

Reverse-Depends
===============
* sagemath [amd64 arm64 armhf i386] (for libflint-arb2)

Packages without architectures listed are reverse-dependencies in: amd64, arm64, armhf, i386, ppc64el, s390x
(AA)apw@brain:~/Downloads/X/boot$ reverse-depends src:sagemath
Reverse-Recommends
==================
* python-sagenb (for sagemath)
* science-mathematics (for sagemath)

Reverse-Depends
===============
* python-sagetex (for sagemath)

Packages without architectures listed are reverse-dependencies in: amd64, arm64, armhf, i386, ppc64el, s390x