Traceback (most recent call last):
  File "precalc.py", line 1338, in <module>
    main()
  File "precalc.py", line 1314, in main
    preprocess()
  File "precalc.py", line 1280, in preprocess
    calc_edit_distances()
  File "precalc.py", line 1181, in calc_edit_distances
    change.save()
  File "C:\Program Files\Python27\lib\site-packages\django\db\models\base.py", line 460, i
n save
    self.save_base(using=using, force_insert=force_insert, force_update=force_update)
  File "C:\Program Files\Python27\lib\site-packages\django\db\models\base.py", line 526, i
n save_base
    rows = manager.using(using).filter(pk=pk_val)._update(values)
  File "C:\Program Files\Python27\lib\site-packages\django\db\models\query.py", line 491,
in _update
    return query.get_compiler(self.db).execute_sql(None)
  File "C:\Program Files\Python27\lib\site-packages\django\db\models\sql\compiler.py", lin
e 869, in execute_sql
    cursor = super(SQLUpdateCompiler, self).execute_sql(result_type)
  File "C:\Program Files\Python27\lib\site-packages\django\db\models\sql\compiler.py", lin
e 735, in execute_sql
    cursor.execute(sql, params)
  File "C:\Program Files\Python27\lib\site-packages\django\db\backends\mysql\base.py", lin
e 86, in execute
    return self.cursor.execute(query, args)
  File "C:\Program Files\Python27\lib\site-packages\MySQLdb\cursors.py", line 174, in exec
ute
    self.errorhandler(self, exc, value)
  File "C:\Program Files\Python27\lib\site-packages\MySQLdb\connections.py", line 36, in d
efaulterrorhandler
    raise errorclass, errorvalue
_mysql_exceptions.OperationalError: (2006, 'MySQL server has gone away')