ansible all -m ping --ask-pass
ERROR! Unexpected Exception: ansible
the full traceback was:

Traceback (most recent call last):
  File "/root/ansible/bin/ansible", line 75, in <module>
    from ansible.cli.adhoc import AdHocCLI as mycli
  File "/root/ansible/lib/ansible/cli/adhoc.py", line 28, in <module>
    from ansible.executor.task_queue_manager import TaskQueueManager
  File "/root/ansible/lib/ansible/executor/task_queue_manager.py", line 28, in <module>
    from ansible.executor.play_iterator import PlayIterator
  File "/root/ansible/lib/ansible/executor/play_iterator.py", line 29, in <module>
    from ansible.playbook.block import Block
  File "/root/ansible/lib/ansible/playbook/__init__.py", line 25, in <module>
    from ansible.playbook.play import Play
  File "/root/ansible/lib/ansible/playbook/play.py", line 27, in <module>
    from ansible.playbook.base import Base
  File "/root/ansible/lib/ansible/playbook/base.py", line 35, in <module>
    from ansible.parsing.dataloader import DataLoader
  File "/root/ansible/lib/ansible/parsing/dataloader.py", line 32, in <module>
    from ansible.parsing.vault import VaultLib
  File "/root/ansible/lib/ansible/parsing/vault/__init__.py", line 67, in <module>
    from cryptography.hazmat.primitives.hashes import SHA256 as c_SHA256
  File "/usr/lib/python2.7/dist-packages/cryptography/hazmat/primitives/hashes.py", line 20, in <module>
    from cryptography.hazmat.backends.interfaces import HashBackend
  File "/usr/lib/python2.7/dist-packages/cryptography/hazmat/backends/__init__.py", line 16, in <module>
    import pkg_resources
  File "/usr/lib/python2.7/dist-packages/pkg_resources.py", line 2876, in <module>
    working_set = WorkingSet._build_master()
  File "/usr/lib/python2.7/dist-packages/pkg_resources.py", line 449, in _build_master
    ws.require(__requires__)
  File "/usr/lib/python2.7/dist-packages/pkg_resources.py", line 745, in require
    needed = self.resolve(parse_requirements(requirements))
  File "/usr/lib/python2.7/dist-packages/pkg_resources.py", line 639, in resolve
    raise DistributionNotFound(req)
DistributionNotFound: ansible