fix(cursor): call initialize after session support check

If a cursor needed to check for session support it would do so, and
then call the `next` function which in most cases would directly
call `_initialize` again - but sometimes would erroneously issue
a `getMore`.

lib/core/cursor.js

@@ -435,7 +435,7 @@ class CoreCursor extends Readable {
           return;
         }
 
-        cursor._next(callback);
+        this._initializeCursor(callback);
       });
 
       return;