Installing Redmine 2.4.x on Debian Lenny

I have to update our company's Redmine installation to the most recent one. The update process consists mostly of some cp -r commands, but bundle will fail due to requiring a ImageMagick version that Debian Lenny did not provide.

Can't install RMagick 2.13.2. You must have ImageMagick 6.4.9 or later.

Instead of going the way to build ImageMagick from scratch or doing some own deb stuff, I adjust the Redmine Gemfile

# Optional gem for exporting the gantt to a PNG file, not supported with jruby
platforms :mri, :mingw do
  group :rmagick do
    # RMagick 2 supports ruby 1.9
    # RMagick 1 would be fine for ruby 1.8 but Bundler does not support
    # different requirements for the same gem on different platforms
    gem "rmagick", "2.12.2"
  end
end

by replacing the given version with 2.12.2

Now

bundle install

installs all dependencies.