Bug#875539: zope2.13: Zope instances fail to start when python-zope.interface is installed.

[Donovan Baarda]

Package: zope2.13
Version: 2.13.22-1
Severity: normal

Dear Maintainer,

After a recent apt-get update and reboot my zope2.13 instances failed
to start. Running:

$ sudo /etc/init.d/zope2.13 start

gave no meaningful output. Running:

$ sudo systemctl status zope2.13

told me that it had "exited" with nothing more helpful. Running:

$ sudo /var/lib/zope2.13/instance/<instance>/bin/runzope

Gave me a traceback indicating an ImportError for zope.event. A search
for event.py found a few instances inside the zope2.13 directories. On
a hunch I looked for other possible 'zope' imports and found:

/usr/lib/python2.7/dist-packages/zope/

This path belonged to the debian package python-zope.interface which
was installed. After uninstalling that package my zope instance
started correctly.

It appears that the /usr/lib/python2.7/dist-packages/zope/ path
installed by python-zope.interface appears earlier in the import paths
and interferes with zope packages provided by zope2.13.

I suggest somehow fixing the python import paths used by zope2.13 so
that it favours modules it provides over other modules provided by
other random packages.

-- System Information:
Debian Release: buster/sid
  APT prefers testing
  APT policy: (500, 'testing'), (300, 'unstable')
Architecture: amd64 (x86_64)

Kernel: Linux 4.12.0-1-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_AU.UTF-8, LC_CTYPE=en_AU.UTF-8 (charmap=UTF-8), LANGUAGE=en_AU:en (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages zope2.13 depends on:
ii  debconf               1.5.63
ii  libc6                 2.24-17
ii  lsb-base              9.20170808
ii  python                2.7.13-2
ii  python-docutils       0.13.1+dfsg-2
ii  python-mechanize      1:0.2.5-3
ii  python-pkg-resources  36.2.7-2
ii  python-tz             2017.2-2
ii  python2.7             2.7.13-2
ii  zope-common           0.5.54

zope2.13 recommends no packages.

Versions of packages zope2.13 suggests:
ii  python [python-profiler]  2.7.13-2
pn  python-unit               <none>

-- no debconf information