Cannot empty the from date when disabling an autoresponse

[tonioo]

Internal Server Error: /user/autoreply/
Traceback (most recent call last):
  File "/srv/modoboa/env/local/lib/python2.7/site-packages/Django-1.7.9-py2.7.egg/django/core/handlers/base.py", line 111, in get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/srv/modoboa/env/local/lib/python2.7/site-packages/Django-1.7.9-py2.7.egg/django/db/transaction.py", line 394, in inner
    return func(*args, **kwargs)
  File "/srv/modoboa/env/local/lib/python2.7/site-packages/Django-1.7.9-py2.7.egg/django/db/transaction.py", line 394, in inner
    return func(*args, **kwargs)
  File "/srv/modoboa/env/local/lib/python2.7/site-packages/Django-1.7.9-py2.7.egg/django/contrib/auth/decorators.py", line 21, in _wrapped_view
    return view_func(request, *args, **kwargs)
  File "/srv/modoboa/env/local/lib/python2.7/site-packages/modoboa_admin/lib.py", line 30, in wrapped_f
    return f(request, *args, **kwargs)
  File "/srv/modoboa/env/local/lib/python2.7/site-packages/modoboa_postfix_autoreply-1.0.2-py2.7.egg/modoboa_postfix_autoreply/views.py", line 35, in autoreply
    arm.save()
  File "/srv/modoboa/env/local/lib/python2.7/site-packages/Django-1.7.9-py2.7.egg/django/db/models/base.py", line 589, in save
    force_update=force_update, update_fields=update_fields)
  File "/srv/modoboa/env/local/lib/python2.7/site-packages/Django-1.7.9-py2.7.egg/django/db/models/base.py", line 617, in save_base
    updated = self._save_table(raw, cls, force_insert, force_update, using, update_fields)
  File "/srv/modoboa/env/local/lib/python2.7/site-packages/Django-1.7.9-py2.7.egg/django/db/models/base.py", line 679, in _save_table
    forced_update)
  File "/srv/modoboa/env/local/lib/python2.7/site-packages/Django-1.7.9-py2.7.egg/django/db/models/base.py", line 723, in _do_update
    return filtered._update(values) > 0
  File "/srv/modoboa/env/local/lib/python2.7/site-packages/Django-1.7.9-py2.7.egg/django/db/models/query.py", line 600, in _update
    return query.get_compiler(self.db).execute_sql(CURSOR)
  File "/srv/modoboa/env/local/lib/python2.7/site-packages/Django-1.7.9-py2.7.egg/django/db/models/sql/compiler.py", line 1005, in execute_sql
    cursor = super(SQLUpdateCompiler, self).execute_sql(result_type)
  File "/srv/modoboa/env/local/lib/python2.7/site-packages/Django-1.7.9-py2.7.egg/django/db/models/sql/compiler.py", line 787, in execute_sql
    cursor.execute(sql, params)
  File "/srv/modoboa/env/local/lib/python2.7/site-packages/Django-1.7.9-py2.7.egg/django/db/backends/utils.py", line 65, in execute
    return self.cursor.execute(sql, params)
  File "/srv/modoboa/env/local/lib/python2.7/site-packages/Django-1.7.9-py2.7.egg/django/db/utils.py", line 94, in __exit__
    six.reraise(dj_exc_type, dj_exc_value, traceback)
  File "/srv/modoboa/env/local/lib/python2.7/site-packages/Django-1.7.9-py2.7.egg/django/db/backends/utils.py", line 65, in execute
    return self.cursor.execute(sql, params)
IntegrityError: null value in column "fromdate" violates not-null constraint