Steps to reproduce

1. create a 2dsphere index with an additional descending field (ascending doesn't trigger the bug)
2. insert a document that doesn't have the additional field set
3. run a geo query $geoWithin with $centerSphere and include the additional secondary field

=> The database will hang indefinitely and a kill -9 is necessary. db.currentOp() shows the query running but db.killOp() has no effect.

Javascript

db.mycoll.drop()
db.mycoll.ensureIndex({"coordinates": "2dsphere", "field": -1})
db.mycoll.insert({"coordinates" : [ -118.240013, 34.073893 ]})
var query = {"coordinates" : {"$geoWithin" : {"$centerSphere" : [[-118.240013, 34.073893], 0.44915760491198753] } }, "field": 1}
db.mycoll.find(query)