subprocess: stdout and stderror seem interchanged or mixed - subprocess

Question

i'm trying to automate interactive ssh calls (see note 1) as follows:
SSHBINARY = '/usr/bin/ssh'
ASKPASS = '/home/mz0/checkHost/askpass.py'
def sshcmd(host,port,user,password,cmd):
env0 = {'SSH_ASKPASS': ASKPASS, 'DISPLAY':':9999'}
ssh = subprocess.Popen([SSHBINARY,"-T","-p %d" % port,
"-oStrictHostKeyChecking=no", "-oUserKnownHostsFile=/dev/null",
"%s#%s" % (user,host), cmd],
stdin=subprocess.PIPE,
stdout=subprocess.PIPE,
stderr=subprocess.PIPE,
env=env0,
preexec_fn=os.setsid
)
error = ssh.stderr.readlines()
result = ssh.stdout.readlines()
return error,result
host = 'localhost'
port = 22
user = 'try1'
password = '1try' # unused, hardcoded in ASKPASS
cmd = 'ls'
result1, error1 = sshcmd(host,port,user,password,cmd)
if result1 : print "OUT: %s" % result1
if error1 : print "ERR: %s" % error1
It turns i'm doing something stupid since i get this:
OUT: ["Warning: Permanently added 'localhost' (RSA) to the list of known hosts.\r\n"]
ERR: ['['Desktop\n', ..., 'Videos\n']']
Obviously stdout and stderr are swapped (note 2). Can you kindly point me my error?
note 1: i'm well aware of password-less ssh, dangers of ignoring host key etc. and hate requests on automating interactive ssh as much as you.
note 2: running the same command in shell confirms that stdout and stderr are swapped in my code
ssh -o 'UserKnownHostsFile /dev/null' -o 'StrictHostKeyChecking no' \
try1#localhost ls > ssh-out 2> ssh-error

Answer 1

return error,result
and
result1, error1 = sshcmd(...)
Just swap either of those around.