Python 3.2 has now its os.environb, the bytes version of os.environ. subprocess should get a new envb argument to be able to use pure bytes environmental variables. Examples:
subprocess.call([b'env], envb={b'PATH': b'/usr/bin'})
and
envb = os.environb.copy()
envb[b'PATH'] = b'/usr/bin'
subprocess.call([b'env], envb=envb)
Specify both env and envb would raise an exception. envb should only be available on POSIX (as os.environb).
Related issues: #8513 (subprocess: support bytes program name) and #8603 (os.environb).