I have tested on mongodb 2.6.2-rc1, the problem still exists. Here is the stack trace:
com.mongodb.CommandResult$CommandFailure: command failed [count]: { "serverUsed" : "localhost/
127.0.0.1:27017" , "errmsg" : "exception: assertion src/mongo/db/query/plan_enumerator.cpp:1011" , "code" : 0 , "ok" : 0.0}
at com.mongodb.CommandResult.getException(CommandResult.java:88)
at com.mongodb.CommandResult.throwOnError(CommandResult.java:134)
at com.mongodb.DBCollection.getCount(DBCollection.java:977)
at com.mongodb.DBCollection.getCount(DBCollection.java:938)
at com.mongodb.DBCollection.getCount(DBCollection.java:913)
at com.mongodb.DBCollection.count(DBCollection.java:860)
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