Moped::Errors::CursorNotFound: The operation: "GET MORE" failed with error "cursor 6633816124113767314 not found"

[doriath]

Check full details on Airbrake: #68608722

Backtrace:

```
[GEM_ROOT]/gems/moped-1.2.7/lib/moped/node.rb:189:in get_more
[GEM_ROOT]/gems/moped-1.2.7/lib/moped/cursor.rb:44:in get_more
[GEM_ROOT]/gems/moped-1.2.7/lib/moped/cursor.rb:29:in each
[GEM_ROOT]/gems/moped-1.2.7/lib/moped/query.rb:77:in each
[GEM_ROOT]/gems/moped-1.2.7/lib/moped/query.rb:77:in each
[GEM_ROOT]/gems/mongoid-3.0.10/lib/mongoid/contextual/mongo.rb:133:in block in each
[GEM_ROOT]/gems/mongoid-3.0.10/lib/mongoid/contextual/mongo.rb:604:in selecting
[GEM_ROOT]/gems/mongoid-3.0.10/lib/mongoid/contextual/mongo.rb:132:in each
[GEM_ROOT]/gems/mongoid-3.0.10/lib/mongoid/contextual.rb:18:in each
[PROJECT_ROOT]/lib/tasks/ranking.rake:6:in block (2 levels) in <top (required)>
[GEM_ROOT]/gems/rake-10.0.3/lib/rake/task.rb:228:in call
[GEM_ROOT]/gems/rake-10.0.3/lib/rake/task.rb:228:in block in execute
[GEM_ROOT]/gems/rake-10.0.3/lib/rake/task.rb:223:in each
[GEM_ROOT]/gems/rake-10.0.3/lib/rake/task.rb:223:in execute
[GEM_ROOT]/gems/rake-10.0.3/lib/rake/task.rb:166:in block in invoke_with_call_chain
/usr/lib/ruby/1.9.1/monitor.rb:211:in mon_synchronize
[GEM_ROOT]/gems/rake-10.0.3/lib/rake/task.rb:159:in invoke_with_call_chain
[GEM_ROOT]/gems/rake-10.0.3/lib/rake/task.rb:152:in invoke
[GEM_ROOT]/gems/rake-10.0.3/lib/rake/application.rb:143:in invoke_task
[GEM_ROOT]/gems/rake-10.0.3/lib/rake/application.rb:101:in block (2 levels) in top_level
[GEM_ROOT]/gems/rake-10.0.3/lib/rake/application.rb:101:in each
[GEM_ROOT]/gems/rake-10.0.3/lib/rake/application.rb:101:in block in top_level
[GEM_ROOT]/gems/rake-10.0.3/lib/rake/application.rb:110:in run_with_threads
[GEM_ROOT]/gems/rake-10.0.3/lib/rake/application.rb:95:in top_level
[GEM_ROOT]/gems/rake-10.0.3/lib/rake/application.rb:73:in block in run
[GEM_ROOT]/gems/rake-10.0.3/lib/rake/application.rb:160:in standard_exception_handling
[GEM_ROOT]/gems/rake-10.0.3/lib/rake/application.rb:70:in run
[GEM_ROOT]/gems/rake-10.0.3/bin/rake:33:in <top (required)>
[GEM_ROOT]/bin/rake:23:in load
[GEM_ROOT]/bin/rake:23:in <main>
```