Upgrade Redmine on labs.r.n

• Let’s upgrade the system to Stretch first, and immediately try to go back to the redmine Debian package (instead of maintaining an installation from the upstream tarball with tons of vendorized Gems). Figuring out who’s responsible to run SQL migration code might be tricky: dpkg will believe we’re upgrading from 3.0~20140825-8~deb8u4, while we’re actually upgrading from a newer version. But db/schema.rb contains the version of our DB and is likely used for ActiveRecord migrations, so let’s inject it in the relevant place before upgrading the system. Worst case, let’s hope that the ActiveRecord migrations are idempotent.
  • Locally patched files (let’s Puppet’ize any remaining change as part of the upgrade):
    • app/models/attachment.rb: let’s try without patching and see if it’s still needed
    • bin/rails: can be dropped
    • config/application.rb and lib/: the patch configures paths depending on $X_DEBIAN_SITEID; should come for free with the Debian package, presumably (actually IIRC that’s where the patch comes from originally)
    • config/configuration.yml has potentially relevant custom settings
    • config/initializers/secret_token.rb will probably be re-generated by the Debian packaging
    • public/dispatch.fcgi: do we need that file at all?
    • public/maintenance.html, public/maintenance.jpg: vaguely useful
    • public/themes/Modula Mojito/: our custom theme
  • We need to upgrade the redmine_git_hosting plugin.
  • While we’re at it, let’s also upgrade the redmine_bootstrap_kit plugin.
  • ensure email notifications still work
  • ensure Git → Redmine integration still works
  • ensure incoming email gateway still works
  • ensure Git hooks (push to mirrors? anything else?) still work

Related issues

• Blocks #13284

Original created by @intrigeri on 11808 (Redmine)