active_support/dependencies.rb:142:in `load_without_new_constant_marking': no such file to load -- mongrel_rails (MissingSourceFile)

from /home/jhipster/.rvm/gems/ruby-1.8.7-head/gems/activesupport-2.2.2/lib/active_support/dependencies.rb:142:in load' from /home/jhipster/.rvm/gems/ruby-1.8.7-head/gems/activesupport-2.2.2/lib/active_support/dependencies.rb:521:innew_constants_in' from /home/jhipster/.rvm/gems/ruby-1.8.7-head/gems/activesupport-2.2.2/lib/active_support/dependencies.rb:142:in load' from /home/jhipster/.rvm/gems/ruby-1.8.7-head/gems/rails-2.2.2/lib/commands/servers/mongrel.rb:64 from /home/jhipster/.rvm/gems/ruby-1.8.7-head/gems/activesupport-2.2.2/lib/active_support/dependencies.rb:153:inrequire' from /home/jhipster/.rvm/gems/ruby-1.8.7-head/gems/activesupport-2.2.2/lib/active_support/dependencies.rb:153:in require' from /home/jhipster/.rvm/gems/ruby-1.8.7-head/gems/activesupport-2.2.2/lib/active_support/dependencies.rb:521:innew_constants_in' from /home/jhipster/.rvm/gems/ruby-1.8.7-head/gems/activesupport-2.2.2/lib/active_support/dependencies.rb:153:in require' from /home/jhipster/.rvm/gems/ruby-1.8.7-head/gems/rails-2.2.2/lib/commands/server.rb:49 from server:3:inrequire' from server:3