Hello. I had lecture about exception & frames on issue3515.

When Lib/subprocess.py (814)'s CreateProcess() raises exception,
p2cread will be freed by refcount GC, but it never happen before
os.remove() because sys.exc_traceback holds reference to frame
which has p2cread.

import subprocess, os

file = open("filename", "w")
try:
    proc = subprocess.Popen("nosuchprogram", stdout=file)
except OSError:
    pass

try:
    raise RuntimeError() # hack to clear previous exc_traceback
except:
    pass

file.close()
os.remove("filename") # runs fine

So, I think subprocess module's practice which relys on refcount GC
is not good. (p2cread is PC/_subprocess.c 's sp_handle_object, so
automatically freed by refcount GC) I don't think attached "adhok.patch"
is enough, but seems to fix this issue at least.