Странна ошибка в Django!

Traceback (most recent call last):
  File "./manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/my_poject/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 399, in execute_from_command_line
    utility.execute()
  File "/my_poject/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 392, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/my_poject/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 261, in fetch_command
    commands = get_commands()
  File "/my_poject/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 107, in get_commands
    apps = settings.INSTALLED_APPS
  File "/my_poject/local/lib/python2.7/site-packages/django/conf/__init__.py", line 54, in __getattr__
    self._setup(name)
  File "/my_poject/local/lib/python2.7/site-packages/django/conf/__init__.py", line 50, in _setup
    self._configure_logging()
  File "/my_poject/local/lib/python2.7/site-packages/django/conf/__init__.py", line 72, in _configure_logging
    from django.utils.log import DEFAULT_LOGGING
  File "/my_poject/local/lib/python2.7/site-packages/django/utils/log.py", line 7, in <module>
    from django.views.debug import ExceptionReporter, get_exception_reporter_filter
  File "/my_poject/local/lib/python2.7/site-packages/django/views/debug.py", line 10, in <module>
    from django.http import (HttpResponse, HttpResponseServerError,
  File "/my_poject/local/lib/python2.7/site-packages/django/http/__init__.py", line 2, in <module>
    from django.http.request import (HttpRequest, QueryDict, UnreadablePostError,
  File "/my_poject/local/lib/python2.7/site-packages/django/http/request.py", line 11, in <module>
    from django.core import signing
  File "/my_poject/local/lib/python2.7/site-packages/django/core/signing.py", line 45, in <module>
    from django.utils.crypto import constant_time_compare, salted_hmac
  File "/my_poject/local/lib/python2.7/site-packages/django/utils/crypto.py", line 6, in <module>
    import hmac
  File "/usr/lib/python2.7/hmac.py", line 8, in <module>
    from operator import _compare_digest as compare_digest
ImportError: cannot import name _compare_digest