[Bug 1807043] Re: when rewriting sources.list ubuntu-release-upgrader doesn't check to see if new release is available

[Stephane Chazelas]

That fix breaks the upgrade (in my case from xenial to bionic) for users
that use a local mirror over HTTPS as the
_sourcesListEntryDownloadable->url_downloadable doesn't support HTTPS.

It comments out the entries and adds:

      2019-02-19 15:13:51,808 DEBUG entry '# deb
https://localmirror.example.com/example/security.ubuntu.com/ubuntu
xenial-security multiverse' was disabled (no Release file)

The "Release file" is there but "url_downloadable" failed to download it
because of the "https" scheme (note: the apt-transport-https package is
installed).

-- 
You received this bug notification because you are a member of Ubuntu
Foundations Bugs, which is subscribed to ubuntu-release-upgrader in
Ubuntu.
https://bugs.launchpad.net/bugs/1807043

Title:
  when rewriting sources.list ubuntu-release-upgrader doesn't check to
  see if new release is available

Status in ubuntu-release-upgrader package in Ubuntu:
  Fix Released
Status in ubuntu-release-upgrader source package in Bionic:
  Fix Released
Status in ubuntu-release-upgrader source package in Cosmic:
  Fix Released

Bug description:
  [Impact]
  When rewriting sources.list entries the release-upgrader doesn't check to see if the distribution to which the system is being upgraded is supported by the archive / PPA. This results in the following error message:

  A problem occurred during the update. This is usually some sort of
  network problem, please check your network connection and retry.

  E:The repository 'http://ppa.launchpad.net/team-xbmc/ppa/ubuntu
  cosmic Release' does not have a Release file.

  If the release-upgrader were to actually check if the release were
  supported then that specific sources entry could be disabled and the
  upgrade may be able to proceed.

  [Test Case]
  The test case involves adding a PPA which doesn't have a release file for the release to which you are upgrading for upgrading to cosmic we can use the team-xbmc ppa.

  1) sudo add-apt-repository ppa:team-xbmc/ppa
  2) do-release-upgrade --frontend DistUpgradeViewText
  3) Observe the error message re "does not have a Release file" and the upgrade cancel.

  With the version of the release upgrader from -proposed you will
  instead see the following message: "Some third party entries in your
  sources.list were disabled.". Then the release upgrade will proceed to
  the calculation phase, you can quit the upgrade after the calculation
  and check /var/log/dist-upgrade/main.log for the following:

  DEBUG entry '# deb http://ppa.launchpad.net/team-xbmc/ppa/ubuntu
  bionic main' was disabled (no Release file)

  [Regression Potential]
  It seems like an oversight that this part of the release-upgrader never did check for Release files and that this is the right thing to do. Its possible that people who were not allowed to upgrade, because they had PPAs without support for the release to which they wanted to upgrade, are now allowed to upgrade and somehow run in to an upgrade failure e.g. a failure to calculate the upgrade. That seems better and more informative than not allowing them to upgrade at all though.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/ubuntu-release-upgrader/+bug/1807043/+subscriptions