Problem redirecting output with Python subprocesses

I've built a command-line build system based on the Python-based tool Scons. Since all the workstations running Scons have to have Python installed, I'd prefer to just do the few driver scripts I need at the top in Python also.

I have been just using

     os.system

during development, but I now have the system ready to go into daily build use and would like to write
results to a log file. I specifically failed trying the 'subprocess' module. I couldn't get it work below one
level when redirecting the stdout and stderr. That is:

       import subprocess

       bldcommand = 'bld.py'

       one = open("stdout.out","w")
       two = open("stderr.err","w")

       subprocess.call(bldcommand,stdout=one,stderr=two,shell=True)

This runs the underlying 'bld.py' command, but fails to run its underlying call to scons, whether done
with 'os.system' or 'subprocess', without its own I/O redirection. If I remove the I/O redirection clauses
in the call above, the 'bld.py' script runs correctly, but of course without I/O redirection at all.

This is all under Windows, by company mandate ... any suggestions would be most appreciated.


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