Major Description
We use singleton objects for the null Avro value, and for each of the primitive Avro schema types. They're initialized with a reference count of 1, and their reference counts are decremented with the avro_whatever_decref methods, but we don't increment them in the "constructor" methods. That causes the reference counts to get wonky. We don't ever free the static singleton instances, so we don't get any memory corruption, but it's still not very clean.