You're correct that debuggers can be sensitive to the timing of the initial breakpoint.
Adding a conformance test would let us confirm your observation, and ensure such regression won't happen in the future. For reference, see 2b40969c58a099f958c58909b666915991a42979.
I'm still approving since the existing tests did not fail and I cannot find a particular reason `process_breakpoint();` must be placed exactly there in the commit history.