[Python-modules-team] Bug#910056: twisted: Missing version constraint on python-attr dependencies

[Stuart Prescott]

Source: twisted
Version: 18.7.0-2
Severity: important

Dear Maintainer,

The python3-twisted package declares "Depends: python3-attr" however it is
not compatible with the version of python3-attr that is in stretch. This
means that partially upgraded systems could have a non-functional twisted
installation and also means that the upload of twisted to stretch-backports
is (partially?) broken.

To fix the partial-upgrade problem, a versioned dependency such as ">> 17.4.0"
is sufficient.

(Andrej, for stretch-backports, a backport of python-attrs fixes the problem.)

I also can't spot the twisted test suite being run in either the sid or the
stretch-backports build logs, is it possible to make the tests run on the
buildd? (Would that have caught this problem with the backport?)

cheers
Stuart



$ python3
Python 3.5.3 (default, Sep 27 2018, 17:25:39) 
[GCC 6.3.0 20170516] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import twisted.web.http
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python3/dist-packages/twisted/web/http.py", line 100, in <module>
    from twisted.internet import interfaces, protocol, address
  File "/usr/lib/python3/dist-packages/twisted/internet/address.py", line 23, in <module>
    class IPv4Address(object):
  File "/usr/lib/python3/dist-packages/twisted/internet/address.py", line 37, in IPv4Address
    type = attr.ib(validator=attr.validators.in_(["TCP", "UDP"]))
AttributeError: module 'attr.validators' has no attribute 'in_'

$ apt-cache policy python3-twisted python3-attr
python3-twisted:
  Installed: 18.7.0-2~bpo9+1
  Candidate: 18.7.0-2~bpo9+1
  Version table:
 *** 18.7.0-2~bpo9+1 200
        200 http://deb.debian.org/debian stretch-backports/main amd64 Packages
        200 http://deb.debian.org/debian stretch-backports/main i386 Packages
        100 /var/lib/dpkg/status
     16.6.0-2 500
        500 http://deb.debian.org/debian stretch/main amd64 Packages
        500 http://deb.debian.org/debian stretch/main i386 Packages
python3-attr:
  Installed: 16.3.0-1
  Candidate: 16.3.0-1
  Version table:
 *** 16.3.0-1 500
        500 http://deb.debian.org/debian stretch/main amd64 Packages
        500 http://deb.debian.org/debian stretch/main i386 Packages
        100 /var/lib/dpkg/status