Fix: fix CVE-2020-28243

Author: errorcode7

docker/transport/sshconn.py

@@ -58,9 +58,7 @@ def f():
  env.pop('SSL_CERT_FILE', None)
 
  self.proc = subprocess.Popen(
- ' '.join(args),
  env=env,
- shell=True,
  stdout=subprocess.PIPE,
  stdin=subprocess.PIPE,
  preexec_fn=None if constants.IS_WINDOWS_PLATFORM else preexec_func)