A sub-millisecond wait is fairly quick, but it depends on the machine speed. I should have included a counter. Try the following. It's not reproducing the problem if num_retries doesn't get incremented.

    import os
    import time

    ERROR_DIR_NOT_EMPTY = 145

    PARENT_PATH = 'foo'
    CHILD_PATH = os.path.join(PARENT_PATH, 'bar')

    os.rmdir(CHILD_PATH)

    num_retries = 0
    t0 = time.perf_counter()

    while True:
        try:
            os.rmdir(PARENT_PATH)
            break
        except OSError as e:
            if e.winerror != ERROR_DIR_NOT_EMPTY:
               raise
            num_retries += 1

    wait_time = time.perf_counter() - t0

    print('num_retries:', num_retries)
    print('wait_time:', wait_time)