Use SafeSql.of("{foo? -> OR foo?}", optionalFoo) instead of
optionally("or {foo}", optionalFoo) because the former allows you to reference
foo? multiple times in the right hand side snippet.
The JIT and the CPU can move the surrounding plain reads and writes across a
checkpoint, so the ordering applies to the check-in calls themselves, not to the SUT code
around them. Use Happenstance.join(K) instead.