Can't login to SUT without password while using ssh backend

[bhargavdas]

While trying to execute test in SUT using ssh backend, if the SUT doesn't have a password runltp-ng is not able to login.

Here is my observation till now,

• Used a raspberry pi yocto build (ltp installed), no password required for login

  bhargav@ubuntu:~/LTP-ng/runltp-ng (master)$ ./runltp-ng --verbose --cmd=/opt/ltp/testcases/bin/write01 --backend=ssh:host=192.168.0.111
  Using ssh backend; parameters 'host=192.168.0.111'
  ssh:password or ssh:key_file must be set! at backend.pm line 608.

• After this I created a password for login

  
  bhargav@ubuntu:~/LTP-ng/runltp-ng (master)$ ./runltp-ng --verbose --cmd=/opt/ltp/testcases/bin/write01 --backend=ssh:host=192.168.0.111:password=123
  Using ssh backend; parameters 'host=192.168.0.111 password=123'
  Waiting for sshd to accept connections
  Starting ssh: export TERM=dumb; script -f -c 'ssh   root@192.168.0.111' /dev/null
  Waiting for prompt
  Waiting for regexp '(?^:[Pp]assword:)'
  ssh: Script started, file is /dev/null
  Writing string '123'
  Writing string '/opt/ltp/testcases/bin/write01; echo cmd-exit-0-$?'
  Waiting for regexp '(?^:cmd-exit-0-\d+)'
  ssh: root@192.168.0.111's password: 
  ssh: Last login: Fri Mar  9 12:54:47 2018 from 192.168.0.112
  ssh: root@raspberrypi3-64:~# /opt/ltp/testcases/bin/write01; echo cmd-exit-0-$?
  ssh: tst_test.c:1311: TINFO: Timeout per run is 0h 05m 00s
  ssh: write01.c:40: TPASS: write() passed
  ssh: 
  ssh: Summary:
  ssh: passed   1
  ssh: failed   0
  ssh: broken   0
  ssh: skipped  0
  ssh: warnings 0
  ssh: cmd-exit-0-0
  Cmd exit value 0
  0
  root@192.168.0.111's password: 
  Last login: Fri Mar  9 12:54:47 2018 from 192.168.0.112
  root@raspberrypi3-64:~# /opt/ltp/testcases/bin/write01; echo cmd-exit-0-$?
  tst_test.c:1311: TINFO: Timeout per run is 0h 05m 00s
  write01.c:40: TPASS: write() passed

Summary: passed 1 failed 0 broken 0 skipped 0 warnings 0 Writing string '! [ -e /opt/ltp ]; echo cmd-exit-1-$?' Waiting for regexp '(?^:cmd-exit-1-\d+)' ssh: root@raspberrypi3-64:~# ! [ -e /opt/ltp ]; echo cmd-exit-1-$? ssh: cmd-exit-1-1 Cmd exit value 1 Writing string 'exit'

Am I missing something here or is this a bug?