Mapreduce into sharded collection with hashed index fails

When outputting from a map reduce job into a sharded output collection which features a hashed index on the _id field, no output is produced. The _id field is also the sharding key, so this issue

Extensive testing shows that this happens only for the first map reduce that is ever run on a MongoDB cluster. It fails to produce output and in the process, the name of the output collection appears to become 'cursed' somehow: Any subsequent map-reduce job runs fail if that same output collection name is used.

Even if the collection is re-created or the entire database is dropped and re-created, or if a different database is used. The name of the output collection can never be used again. Only when outputting into a collection with a different name, the exact same map reduce job processing the exact same data will succeed.

The problem emerges on sharded clusters only, and only when the output collection uses a hashed index.

It is possible to work around this problem by running a dummy map reduce job on newly setup MongoDB clusters, using an output collection that will never be used in regular operations.