Why am I not getting the full git clone output here?

foo.py

# assume all imports are done

#Old: proc = subprocess.Popen(['git', 'clone', '[url here]'], stdout=subprocess.PIPE, stderr=subprocess.PIPE)

# Fixed
proc = subprocess.Popen(['git', 'clone', '--progress' '[url here]'],
                        stdout=subprocess.PIPE,
                        stderr=subprocess.STDOUT)

while proc.poll() is None:
    out = proc.stdout.readline()
    print out

output.txt

Works as expected