If the user specifies a batch size of 1, the driver must use a batch size of 2 for the initial query, because the server treats nToReturn of 1 in OP_QUERY the same as -1: it closes the cursor after the first batch.

In PyMongo we override batch size of 1 with 2, not just for OP_QUERY but for OP_GET_MORE too.

Let us specify that drivers use batch size 2 instead of 1 for OP_QUERY only, not for OP_GET_MORE.

Let us also discover the history and intent of the server's quirky OP_QUERY behavior, and investigate whether the "find" command will act the same.