Why does bufsize=1 not work in subprocess.Popen ?

I read in the docs that "bufsize=1" causes line buffering. (for
subprocess.Popen)

The following tiny program launches an executable file and then receives
its output. That works, but I want to
receive each line as it is ouput, not all of the lines at termination,
which is what is happening.
-------------------------------------------------------
from subprocess import Popen, PIPE
from os import remove, sep

p = Popen("." + sep + "myprogram", stdout=PIPE, bufsize=1)

while(1):
    line = p.stdout.readline() # get next line
    print line,
    if line.count("terminator"):
        break
------------------------------------------------------
How can I get line buffering?

Mitchell Timin

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