[Python-apps-team] Bug#919078: buildbot: upgrading a buildmaster from 0.8 fails the hard way

[Paolo Greppi]

Package: buildbot
Version: 1.6.0-1
Severity: normal

Dear Maintainer,

when I try to upgrade from stretch to buster a system with buildbot installed
and a buildmaster service configured:
  
  apt update && apt dist-upgrade
  
after upgrading to buildbot 1.x it tries to configure it, but the buildmaster
service fails to start therefore apt stops the hard way (with a broken install)

to make the buster migration run smooth, it would be great if buildbot on
upgrading from 0.8 to 1.x were to:
1) disable the service, so that apt can complete the dist-upgrade command
2) prominently display a message that the upgrade from buildbot 0.8 to 1.x
   requires manual actions:
   - fix the buildmaster config syntax
   - wipe the DB
   - invoke buildbot upgrade-master /var/lib/buildbot/masters/xxx
   - and manually re-enable builmaster service
   see: http://docs.buildbot.net/latest/manual/upgrading/nine-upgrade.html#upgrading-to-nine
3) point out that in buster we don't have the buildbot Web Status widget
   anymore, and suggest a workaround

Thanks !

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

Kernel: Linux 4.9.0-6-amd64 (SMP w/4 CPU cores)
Locale: LANG=it_IT.UTF-8, LC_CTYPE=it_IT.UTF-8 (charmap=UTF-8), LANGUAGE=it_IT.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages buildbot depends on:
ii  python3-buildbot  1.6.0-1

buildbot recommends no packages.

buildbot suggests no packages.

-- Configuration Files:
/etc/default/buildmaster changed [not included]
/etc/init.d/buildmaster changed [not included]

-- no debconf information