[DRE-maint] Bug#1031685: redmine doesn't work as thin instance

[Andre Heider]

Package: redmine
Version: 5.0.4-2~bpo11+1

I've a ~3 year old redmine+thin+nginx oldstable setup which I couldn't 
use since upgrading to bullseye. Now that there's a backport (many 
thanks for finally having one!), I tried to get that old instance 
working again.

It seems the packages have been updated and the databases migrated just 
fine.

The thin instance is also started:
2023-02-20 15:26:44 +0100 Writing PID to /run/redmine/redmine.0.pid
2023-02-20 15:26:44 +0100 Changing process privilege to www-data:www-data
2023-02-20 15:26:44 +0100 Using rack adapter
2023-02-20 15:27:14 +0100 Thin web server (v1.8.0 codename Possessed Pickle)
2023-02-20 15:27:14 +0100 Maximum connections set to 1024
2023-02-20 15:27:14 +0100 Listening on /run/redmine/redmine.0.sock, 
CTRL+C to stop

But upon the first request it errors out:

2023-02-20 15:27:18 +0100 Exiting!
/usr/lib/ruby/vendor_ruby/zeitwerk/kernel.rb:34:in `require': cannot 
load such file -- thin/request (LoadError)
     from /usr/lib/ruby/vendor_ruby/zeitwerk/kernel.rb:34:in `require'
     from 
/usr/lib/aarch64-linux-gnu/rubygems-integration/2.7.0/gems/thin-1.8.0/lib/thin/connection.rb:31:in 
`post_init'
     from /usr/lib/ruby/vendor_ruby/em/connection.rb:58:in `block in new'
     from /usr/lib/ruby/vendor_ruby/em/connection.rb:49:in `instance_eval'
     from /usr/lib/ruby/vendor_ruby/em/connection.rb:49:in `new'
     from /usr/lib/ruby/vendor_ruby/eventmachine.rb:1526:in `event_callback'
     from /usr/lib/ruby/vendor_ruby/eventmachine.rb:196:in `run_machine'
     from /usr/lib/ruby/vendor_ruby/eventmachine.rb:196:in `run'
     from 
/usr/lib/aarch64-linux-gnu/rubygems-integration/2.7.0/gems/thin-1.8.0/lib/thin/backends/base.rb:75:in 
`start'
     from 
/usr/lib/aarch64-linux-gnu/rubygems-integration/2.7.0/gems/thin-1.8.0/lib/thin/server.rb:162:in 
`start'
     from 
/usr/lib/aarch64-linux-gnu/rubygems-integration/2.7.0/gems/thin-1.8.0/lib/thin/controllers/controller.rb:87:in 
`start'
     from 
/usr/lib/aarch64-linux-gnu/rubygems-integration/2.7.0/gems/thin-1.8.0/lib/thin/runner.rb:203:in 
`run_command'
     from 
/usr/lib/aarch64-linux-gnu/rubygems-integration/2.7.0/gems/thin-1.8.0/lib/thin/runner.rb:159:in 
`run!'
     from 
/usr/lib/aarch64-linux-gnu/rubygems-integration/2.7.0/gems/thin-1.8.0/bin/thin:6:in 
`<top (required)>'
     from /usr/bin/thin:23:in `load'
     from /usr/bin/thin:23:in `<main>'

Adding "gem 'thin'" to /usr/share/redmine/Gemfile fixes it for me.

I've no idea about ruby stuff, so that's probably not an appropriate 
solution. Does this need to be fixed or can I solve that without 
modifying the package's Gemfile?

Thanks and Cheers,
Andre