Bug#915235: cypari2 FTBFS with Python 3.7 as default

[Adrian Bunk]

Source: cypari2
Version: 1.2.1-1
Severity: serious
Tags: ftbfs

https://tests.reproducible-builds.org/debian/rb-pkg/unstable/amd64/cypari2.html

...
x86_64-linux-gnu-gcc -pthread -DNDEBUG -g -fwrapv -O2 -Wall -g -O2 -ffile-prefix-map=/build/1st/cypari2-1.2.1=. -fstack-protector-strong -Wformat -Werror=format-security -Wdate-time -D_FORTIFY_SOURCE=2 -fPIC -I./cypari2 -I/usr/lib/python3/dist-packages/cysignals -I/usr/include/python3.6m -c cypari2/closure.c -o build/temp.linux-amd64-3.6/cypari2/closure.o
cypari2/closure.c:29:10: fatal error: Python.h: No such file or directory
 #include "Python.h"
          ^~~~~~~~~~
compilation terminated.
error: command 'x86_64-linux-gnu-gcc' failed with exit status 1
E: pybuild pybuild:338: build: plugin distutils failed with: exit code=1: /usr/bin/python3.6 setup.py build 
dh_auto_build: pybuild --build -i python{version} -p "3.6 3.7" returned exit code 13
make[1]: *** [debian/rules:12: override_dh_auto_build] Error 25



The build dependencies include:
  libpython3-dev, libpython3.7-dev

These should be replaced with:
  libpython3-all-dev