Redmine

Hi,
being completely new to redmine, I tried to install the redmine_git_hosting plugin, following the instructions at
https://jbox-web.github.io/redmine_git_hosting/howtos/index.html#step-by-step-installation

Something seems to have gone wrong, yet redmine was still functional. Following the author's suggestion, I tried running

RAILS_ENV=production NAME=redmine_git_hosting rake redmine:plugins:migrate

to debug the problems, now all I get is this:

[redmine@myhost redmine]$ RAILS_ENV=production NAME=redmine_git_hosting rake redmine:plugins:migrate
/usr/local/rvm/rubies/ruby-2.0.0-p353/lib/ruby/2.0.0/x86_64-linux/psych.so: warning: already initialized constant Psych::Parser::ANY
/usr/local/rvm/rubies/ruby-2.0.0-p353/lib/ruby/2.0.0/x86_64-linux/psych.so: warning: already initialized constant Psych::Parser::UTF8
/usr/local/rvm/rubies/ruby-2.0.0-p353/lib/ruby/2.0.0/x86_64-linux/psych.so: warning: already initialized constant Psych::Parser::UTF16LE
/usr/local/rvm/rubies/ruby-2.0.0-p353/lib/ruby/2.0.0/x86_64-linux/psych.so: warning: already initialized constant Psych::Parser::UTF16BE
rake aborted!
TypeError: superclass mismatch for class SyntaxError
/usr/local/rvm/gems/ruby-2.0.0-p353/gems/activesupport-3.2.16/lib/active_support/ordered_hash.rb:2:in `require'
/usr/local/rvm/gems/ruby-2.0.0-p353/gems/activesupport-3.2.16/lib/active_support/ordered_hash.rb:2:in `<top (required)>'
/usr/local/rvm/gems/ruby-2.0.0-p353/gems/activesupport-3.2.16/lib/active_support/ordered_options.rb:1:in `require'
/usr/local/rvm/gems/ruby-2.0.0-p353/gems/activesupport-3.2.16/lib/active_support/ordered_options.rb:1:in `<top (required)>'
/usr/local/rvm/gems/ruby-2.0.0-p353/gems/railties-3.2.16/lib/rails/configuration.rb:2:in `require'
/usr/local/rvm/gems/ruby-2.0.0-p353/gems/railties-3.2.16/lib/rails/configuration.rb:2:in `<top (required)>'
/usr/local/rvm/gems/ruby-2.0.0-p353/gems/railties-3.2.16/lib/rails/railtie.rb:2:in `require'
/usr/local/rvm/gems/ruby-2.0.0-p353/gems/railties-3.2.16/lib/rails/railtie.rb:2:in `<top (required)>'
/usr/local/rvm/gems/ruby-2.0.0-p353/gems/railties-3.2.16/lib/rails/engine.rb:1:in `require'
/usr/local/rvm/gems/ruby-2.0.0-p353/gems/railties-3.2.16/lib/rails/engine.rb:1:in `<top (required)>'
/usr/local/rvm/gems/ruby-2.0.0-p353/gems/railties-3.2.16/lib/rails/plugin.rb:1:in `require'
/usr/local/rvm/gems/ruby-2.0.0-p353/gems/railties-3.2.16/lib/rails/plugin.rb:1:in `<top (required)>'
/usr/local/rvm/gems/ruby-2.0.0-p353/gems/railties-3.2.16/lib/rails/application.rb:3:in `require'
/usr/local/rvm/gems/ruby-2.0.0-p353/gems/railties-3.2.16/lib/rails/application.rb:3:in `<top (required)>'
/usr/local/rvm/gems/ruby-2.0.0-p353/gems/railties-3.2.16/lib/rails.rb:10:in `require'
/usr/local/rvm/gems/ruby-2.0.0-p353/gems/railties-3.2.16/lib/rails.rb:10:in `<top (required)>'
/usr/local/rvm/gems/ruby-2.0.0-p353/gems/railties-3.2.16/lib/rails/all.rb:1:in `require'
/usr/local/rvm/gems/ruby-2.0.0-p353/gems/railties-3.2.16/lib/rails/all.rb:1:in `<top (required)>'
/opt/redmine/config/application.rb:3:in `require'
/opt/redmine/config/application.rb:3:in `<top (required)>'
/opt/redmine/Rakefile:5:in `require'
/opt/redmine/Rakefile:5:in `<top (required)>'
/usr/local/rvm/gems/ruby-2.0.0-p353/bin/ruby_executable_hooks:15:in `eval'
/usr/local/rvm/gems/ruby-2.0.0-p353/bin/ruby_executable_hooks:15:in `<main>'
(See full trace by running task with --trace)

I tried googling this, but could not come up with anything I could've used directly - So maybe someone can give me a hint, how this could have happend and how to resolve this.

Thanks in advance!
Daniel

My environment:

[redmine@myhost redmine]$ bundle --version
Bundler version 1.6.4

[redmine@myhost redmine]$ ruby -v
ruby 2.0.0p353 (2013-11-22 revision 43784) [x86_64-linux]

[redmine@myhost redmine]$ bundle --version
Bundler version 1.6.4