Fehler nach Aktualisierung von Server 14.04 auf 16.04 bei Firefox Sync Server

Traceback (most recent call last):
  File "./local/bin/gunicorn", line 7, in <module>  
    from gunicorn.app.wsgiapp import run
  File "/opt/syncserver/local/local/lib/python2.7/site-packages/gunicorn/app/wsgiapp.py", line 10, in <module>  
    from gunicorn.app.base import Application
  File "/opt/syncserver/local/local/lib/python2.7/site-packages/gunicorn/app/base.py", line 10, in <module>  
    from gunicorn import util
  File "/opt/syncserver/local/local/lib/python2.7/site-packages/gunicorn/util.py", line 7, in <module>  
    import email.utils
  File "/usr/lib/python2.7/email/utils.py", line 32, in <module>  
    from email._parseaddr import quote
  File "/usr/lib/python2.7/email/_parseaddr.py", line 16, in <module>  
    import time, calendar
  File "/usr/lib/python2.7/calendar.py", line 9, in <module>  
    import datetime
ImportError: No module named datetime
Makefile:46: die Regel für Ziel „serve“ scheiterte
make: *** [serve] Fehler 1

#!/bin/sh
cd /opt/syncserver
wait 1
make serve