I ran across this problem in Python 2.3.3 and see it is
still there in 2.4.2.

When running the test_pty.py test case, I would get
intermittant failures depending on how the test was
invoked or the compiler flags used on Solaris. 
Trussing the interpreter while running the test revealed:
ioctl(4, I_PUSH, "ptem\xff^T^F^H")  Err#22 EINVAL

There was garbage on the end of the string when it
would fail.

I tracked the problem back to fcntl_ioctl() in
fcntlmodule.c.  The string was not being NULL
terminated, but relied on having zeroed gargage on the
stack to work.

I checked the source for 2.4.2 and noticed the same
problem.  Patch to fix the problem is attached.