Git authentication as root from Python script doesn't work even when demoted -

i have python script needs run in sudo mode , should run git commands (among them clone , push). these commands can't connect server, because run root , such don't use normal-user ssh key.

so far it's common problem, thing trying demote user before calling these commands. used:

def bash_background_demoted(cmd_list):     def _demote():         if getuid() == 0:             user = getenv('sudo_user')         else:             user = getenv('user')         uid, gid = pwd.getpwnam(user)[2:4]         setegid(gid)         seteuid(uid)      process = popen(cmd_list, stdout = pipe, stderr = pipe, preexec_fn = _demote)     outp, err = process.communicate()     print outp + err 

this method seems work on other commands, not on git:

bash_background_demoted(['whoami']) # mark bash_background_demoted(['git', 'clone', 'ssh://git@bitbucket.org/stuff', '/repo/dir/']) # permission denied (publickey). # fatal: remote end hung unexpectedly 

if don't run sudo, work (but other parts break, it's not acceptable solution).

the -i [keyfile] argument doesn't exist push. know solution? trivial, i'm stuck...

edit: home environment variable set correctly in main process , subprocess. user isn't set correctly, setting doesn't change error.

edit2: i've verified keys causing problem. copies mine /root/.ssh/ , errors went away. not solution though.

(the solution needs work on ubuntu in recent version of python 2)

what home environment variable set to? make sure points mark's home , not root's.