Rewinding a tailable cursor with an empty first batch results in a getMore command being executed. This is demonstrated for both change streams and basic, tailable cursors in the attached scripts.

PHPC-1050 originally touched on this issue by ensuring that a getMore was not executed at the time the cursor was constructed; however, it only punted it to the first iteration even on the cursor (be it rewind() or next()).

This issue is responsible for PHPLIB-451 and the related spec test failure in PHPLIB-416. While PHPLIB-451 can work around the issue on its own by inspecting the firstBatch field in the initial aggregate response, we should still see if this can be addressed in PHPC itself.