This alignment is strange since it aligns with the code. Is there not a way to adjust the indentation, or move the curly brace to a new line?

This happens elsewhere as well.

That's uncrustify... I ended up shortening the test case name in da38188.

Why is iteration_start_time needed? Why can't you just use std::this_thread::sleep_for(delay) instead of sleep_until?

To avoid the time it takes to actually execute the loop code from adding up. Also, std::this_thread::sleep_for makes no guarantees as to which clock is used.

I guess I mean something like:

#define SLEEP_AND_RETRY_UNTIL(delay, timeout) \
  for (auto start = std::chrono::steady_clock::now(); \ 
       std::chrono::steady_clock::now() - start < timeout; \
       std::this_thread::sleep_for(delay))

If you'd rather leave it as is, then I'm fine with it. It just seems like your use case doesn't require such precision.

I didn't want to lose retries due to non-negligible execution times, but it is true that these timeouts are pretty arbitrary anyways.

Sure, why not. See 4d85be9.

This added line can be removed

Done in da38188.