flapjack build failing with ruby 2.1.1, bundler 1.5.3, "Could not find rake-10.3.1 in any of the sources (Bundler::GemNotFound)"

fail.txt

[builder:flapjack] Executing: `/opt/flapjack/embedded/bin/bundle exec rake build` with cwd=/var/cache/omnibus/src/flapjack,timeout=5400,env="RUBYOPT= BUNDLE_BIN_PATH= BUNDLE_GEMFILE= GEM_PATH= GEM_HOME="
[builder:flapjack] /opt/flapjack/embedded/bin/bundle command failed, 0.566573754s
[builder:flapjack] Failed to execute cmd ["/opt/flapjack/embedded/bin/bundle exec rake build", {:cwd=>"/var/cache/omnibus/src/flapjack", :timeout=>5400, :env=>{"RUBYOPT"=>nil, "BUNDLE_BIN_PATH"=>nil, "BUNDLE_GEMFILE"=>nil, "GEM_PATH"=>nil, "GEM_HOME"=>nil}}] 3 time(s). Retrying in 20s.
[builder:flapjack] Executing: `/opt/flapjack/embedded/bin/bundle exec rake build` with cwd=/var/cache/omnibus/src/flapjack,timeout=5400,env="RUBYOPT= BUNDLE_BIN_PATH= BUNDLE_GEMFILE= GEM_PATH= GEM_HOME="
[builder:flapjack] /opt/flapjack/embedded/bin/bundle command failed, 0.589301236s
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Failed to build flapjack while running `/opt/flapjack/embedded/bin/bundle exec rake build` with cwd=/var/cache/omnibus/src/flapjack,timeout=5400,env="RUBYOPT= BUNDLE_BIN_PATH= BUNDLE_GEMFILE= GEM_PATH= GEM_HOME="
Exception:
  Mixlib::ShellOut::ShellCommandFailed: Expected process to exit with [0], but received '1'
  ---- Begin output of /opt/flapjack/embedded/bin/bundle exec rake build ----
  STDOUT:
  STDERR: /opt/flapjack/embedded/lib/ruby/gems/2.1.0/gems/bundler-1.5.3/lib/bundler/spec_set.rb:92:in `block in materialize': Could not find rake-10.3.1 in any of the sources (Bundler::GemNotFound)
  	from /opt/flapjack/embedded/lib/ruby/gems/2.1.0/gems/bundler-1.5.3/lib/bundler/spec_set.rb:85:in `map!'

Failed to build flapjack while running /opt/flapjack/embedded/bin/bundle install --path=/opt/flapjack/embedded/service/gem with cwd=/var/cache/omnibus/src/flapjack,timeout=5400
Exception: