popen4 poll problems

[Jim]

Hi,

I noticed with popen2.Popen4 class, sometimes the poll() method will
keep returning -1 although the command has finished.

However, when a read is done ( ex. p4instance.fromchild.read() ) and
then a poll is done, poll() will return the process exit value.

Why does this happen? perhaps I have to do some type of flush before
doing poll?

Thanks in advance
Cheers,
Jim