Bug#898401: python3.6: causes regressions in testing when python3-defaults is not also upgraded
tl;dr: please consider giving python3.6 a Breaks on
python3-all (<< 3.6.5~rc1-1), python3-dev (<< 3.6.5~rc1-1),
python3-venv (<< 3.6.5-2) so the testing infrastructure knows that
they must migrate together.
python3.6 in unstable is marked as causing autopkgtest regressions when
the CI infrastructure tries to migrate it to testing, causing a
substantial migration delay.
One of those regressions is in src:python-numpy. When python-numpy from
testing is tested with src:python3.6 upgraded to their unstable versions
("trigger: python3.6" in
the distutils module is missing:
=== python3.6 ===
Traceback (most recent call last):
File "setup.py", line 10, in <module>
from numpy.distutils.core import setup
File "/usr/lib/python3/dist-packages/numpy/distutils/__init__.py", line 8, in <module>
from . import ccompiler
File "/usr/lib/python3/dist-packages/numpy/distutils/ccompiler.py", line 10, in <module>
from distutils import ccompiler
ImportError: cannot import name 'ccompiler'
In a complete upgrade to unstable, python-numpy passes tests:
This appears to be because python3.6 dropped its dependency on
python3-distutils in 3.6.5~rc1-2 (#893755, #893847), which was later
mitigated by adding python3-distutils dependencies in python3-all,
python3-dev and python3-venv. The CI infrastructure can't know that
src:python3-defaults needs to migrate along with src:python3.6 unless
a dependency or Breaks relationship says so.
Similar autopkgtest regressions in src:link-grammar look as though they
would also be addressed by this change.
The autopkgtest regressions in src:caffe and src:gpaw would not be
addressed by this change, because they do not pull in python3-dev.