We ran into that in https://github.com/grpc/grpc/issues/12886. Passing GPR_TIMESPAN to C core with a semantics of "timeout" has worked in the past, and it seems it stopped working after https://github.com/grpc/grpc/pull/12677. Not urgent, but might be worth fixing in the future.
