message: test: Format predicate source as multiline on error
  Github-Pull:
  Rebased-From:
diff: @@ -219,7 +219,7 @@ def wait_until(predicate, *, attempts=float('inf'), timeout=float('inf'), lock=N
  time.sleep(0.05)
  # Print the cause of the timeout
  - predicate_source = inspect.getsourcelines(predicate)
  + predicate_source = "''''\n" + inspect.getsource(predicate) + "'''"
  logger.error("wait_until() failed. Predicate: {}".format(predicate_source))
  if attempt >= attempts:
  raise AssertionError("Predicate {} not true after {} attempts".format(predicate_source, attempts))
  