Travis failing mysteriously

[danascheider]

Travis fails when running rake with the default task of rake appraisal:run (see Rakefile). I get the following output and I am at my wit's end.

$ bundle exec rake
appraisal install
>> bundle check --gemfile='/home/travis/build/danascheider/sinatra-sequel_extension/gemfiles/sinatra_1.1.gemfile' || bundle install --gemfile='/home/travis/build/danascheider/sinatra-sequel_extension/gemfiles/sinatra_1.1.gemfile'
/home/travis/.rvm/rubies/ruby-1.9.3-p547/lib/ruby/site_ruby/1.9.1/rubygems/dependency.rb:313:in `to_specs': Could not find 'bundler' (>= 0) among 26 total gem(s) (Gem::LoadError)
Checked in 'GEM_PATH=/home/travis/build/danascheider/sinatra-sequel_extension/vendor/bundle/ruby/1.9.1', execute `gem env` for more information
    from /home/travis/.rvm/rubies/ruby-1.9.3-p547/lib/ruby/site_ruby/1.9.1/rubygems/dependency.rb:322:in `to_spec'
    from /home/travis/.rvm/rubies/ruby-1.9.3-p547/lib/ruby/site_ruby/1.9.1/rubygems/core_ext/kernel_gem.rb:58:in `gem'
    from /home/travis/.rvm/gems/ruby-1.9.3-p547@global/bin/bundle:22:in `'
    from /home/travis/.rvm/gems/ruby-1.9.3-p547/bin/ruby_executable_hooks:15:in `eval'
    from /home/travis/.rvm/gems/ruby-1.9.3-p547/bin/ruby_executable_hooks:15:in `'
/home/travis/.rvm/rubies/ruby-1.9.3-p547/lib/ruby/site_ruby/1.9.1/rubygems/dependency.rb:313:in `to_specs': Could not find 'bundler' (>= 0) among 26 total gem(s) (Gem::LoadError)
Checked in 'GEM_PATH=/home/travis/build/danascheider/sinatra-sequel_extension/vendor/bundle/ruby/1.9.1', execute `gem env` for more information
    from /home/travis/.rvm/rubies/ruby-1.9.3-p547/lib/ruby/site_ruby/1.9.1/rubygems/dependency.rb:322:in `to_spec'
    from /home/travis/.rvm/rubies/ruby-1.9.3-p547/lib/ruby/site_ruby/1.9.1/rubygems/core_ext/kernel_gem.rb:58:in `gem'
    from /home/travis/.rvm/gems/ruby-1.9.3-p547@global/bin/bundle:22:in `'
    from /home/travis/.rvm/gems/ruby-1.9.3-p547/bin/ruby_executable_hooks:15:in `eval'
    from /home/travis/.rvm/gems/ruby-1.9.3-p547/bin/ruby_executable_hooks:15:in `'
rake aborted!
Command failed with status (1): [appraisal install...]
/home/travis/build/danascheider/sinatra-sequel_extension/Rakefile:13:in `block (2 levels) in '
Tasks: TOP => default => appraisal:run => appraisal:install
(See full trace by running task with --trace)

The command bundle exec rake exited with 1.

Until/unless someone else duplicates this problem it is not a high priority for me as I cannot reproduce it locally and Travis doesn't give me enough information to solve the problem in a time-efficient manner.