Python: get the return code of ant sub-process in windows

Question

I use python to call ant, I want to get the return code of the ant for detect ant error.

for example, in cmd.exe,

C:\Documents and Settings\Administrator>ant sfsf
Buildfile: build.xml does not exist!
Build failed
C:\Documents and Settings\Administrator>echo %ERRORLEVEL%
1

but in python:

>>> a = subprocess.Popen("ant hahah",shell=True)
>>> Buildfile: build.xml does not exist! 
Build failed

>>> a.wait() 
0

Because ant is a bat file, so I must use shell=True to call the Popen. So how can I get the return code (1) in Python?

EDIT: I found use "call ant ..." will solve this problem, thanks for the answers.

Answer 1

My idea to solve this: Get some regex on the output stream. If typical Keywords occur like "Error" you will be informed.

Answer 2

Perhaps this post and a followup will help.