Following https://pypi.python.org/pypi/tqdm#redirecting-writing, I get AttributeError: 'DummyTqdmFile' object has no attribute 'flush' if trying to redirect output to sys.stdout/stderr through tqdm first.

This error fired due to an interaction with the eventlet package where that package calls sys.stderr.flush()

Traceback (most recent call last):
File "ReadQueues.py", line 1286, in
main(sys.argv)
File "ReadQueues.py", line 1243, in main
if not SkipDownload: processAllQueues(cfgglob)
File "ReadQueues.py", line 1093, in processAllQueues
for (que_data,spec_section,bar) in SQSpool.imap(doQueueDownload,arSects):
File "C:\Program Files\Python\27\lib\site-packages\eventlet\greenpool.py", line 244, in next
val = self.waiters.get().wait()
File "C:\Program Files\Python\27\lib\site-packages\eventlet\greenthread.py", line 179, in wait
return self._exit_event.wait()
File "C:\Program Files\Python\27\lib\site-packages\eventlet\event.py", line 121, in wait
return hubs.get_hub().switch()
File "C:\Program Files\Python\27\lib\site-packages\eventlet\hubs\hub.py", line 295, in switch
return self.greenlet.switch()
File "C:\Program Files\Python\27\lib\site-packages\eventlet\hubs\hub.py", line 337, in run
self.fire_timers(self.clock())
File "C:\Program Files\Python\27\lib\site-packages\eventlet\hubs\hub.py", line 462, in fire_timers
self.squelch_timer_exception(timer, sys.exc_info())
File "C:\Program Files\Python\27\lib\site-packages\eventlet\hubs\hub.py", line 387, in squelch_timer_exception
sys.stderr.flush()
AttributeError: 'DummyTqdmFile' object has no attribute 'flush'
I've now added

    def flush(self):
        fp_flush = getattr(self.file, 'flush', lambda: None)
        fp_flush()

to the DummyTqdmFile class in my code.
Full class def is now

  from tqdm import tqdm
  import contextlib
  class DummyTqdmFile(object):
    """Dummy file-like that will write to tqdm"""
    file = None
    def __init__(self, file):
        self.file = file
    def flush(self):
        fp_flush = getattr(self.file, 'flush', lambda: None)
        fp_flush()
    def write(self, x):
        # Avoid print() second call (useless \n)
        if len(x.rstrip()) > 0:
            tqdm.write(x, file=self.file)

If that works, I suggest you revise the documentation at tqdm#redirecting-writing accordingly