Traceback (most recent call last):
  File "/usr/local/lib/python3.4/site-packages/celery/app/trace.py", line 367, in trace_task
    R = retval = fun(*args, **kwargs)
  File "/usr/local/lib/python3.4/site-packages/celery/app/trace.py", line 622, in __protected_call__
    return self.run(*args, **kwargs)
  File "/usr/local/lib/python3.4/site-packages/celery/app/base.py", line 474, in run
    raise task.retry(exc=exc, **retry_kwargs)
  File "/usr/local/lib/python3.4/site-packages/celery/app/task.py", line 668, in retry
    raise_with_context(exc)
  File "/usr/local/lib/python3.4/site-packages/celery/app/base.py", line 472, in run
    return task._orig_run(*args, **kwargs)
  File "/coras-exchange/reservations/tasks.py", line 29, in update_transaction_state
    db_session.add(transaction)
  File "/usr/local/lib/python3.4/contextlib.py", line 66, in __exit__
    next(self.gen)
  File "/coras-exchange/core/db/session.py", line 23, in session_scope
    session.commit()
  File "/usr/local/lib/python3.4/site-packages/sqlalchemy/orm/session.py", line 874, in commit
    self.transaction.commit()
  File "/usr/local/lib/python3.4/site-packages/sqlalchemy/orm/session.py", line 461, in commit
    self._prepare_impl()
  File "/usr/local/lib/python3.4/site-packages/sqlalchemy/orm/session.py", line 441, in _prepare_impl
    self.session.flush()
  File "/usr/local/lib/python3.4/site-packages/sqlalchemy/orm/session.py", line 2136, in flush
    self._flush(objects)
  File "/usr/local/lib/python3.4/site-packages/sqlalchemy/orm/session.py", line 2254, in _flush
    transaction.rollback(_capture_exception=True)
  File "/usr/local/lib/python3.4/site-packages/sqlalchemy/util/langhelpers.py", line 60, in __exit__
    compat.reraise(exc_type, exc_value, exc_tb)
  File "/usr/local/lib/python3.4/site-packages/sqlalchemy/util/compat.py", line 186, in reraise
    raise value
  File "/usr/local/lib/python3.4/site-packages/sqlalchemy/orm/session.py", line 2218, in _flush
    flush_context.execute()
  File "/usr/local/lib/python3.4/site-packages/sqlalchemy/orm/unitofwork.py", line 386, in execute
    rec.execute(self)
  File "/usr/local/lib/python3.4/site-packages/sqlalchemy/orm/unitofwork.py", line 545, in execute
    uow
  File "/usr/local/lib/python3.4/site-packages/sqlalchemy/orm/persistence.py", line 162, in save_obj
    for table, mapper in base_mapper._sorted_tables.items():
  File "/usr/local/lib/python3.4/site-packages/sqlalchemy/util/langhelpers.py", line 754, in __get__
    obj.__dict__[self.__name__] = result = self.fget(obj)
  File "/usr/local/lib/python3.4/site-packages/sqlalchemy/orm/mapper.py", line 2737, in _sorted_tables
    extra_dependencies=extra_dependencies)
  File "/usr/local/lib/python3.4/site-packages/sqlalchemy/sql/ddl.py", line 996, in sort_tables
    tables, filter_fn=_skip_fn, extra_dependencies=extra_dependencies)
  File "/usr/local/lib/python3.4/site-packages/sqlalchemy/sql/ddl.py", line 1057, in sort_tables_and_constraints
    filtered = filter_fn(fkc)
  File "/usr/local/lib/python3.4/site-packages/sqlalchemy/sql/ddl.py", line 986, in _skip_fn
    if skip_fn(fk):
  File "/usr/local/lib/python3.4/site-packages/sqlalchemy/orm/mapper.py", line 2721, in skip
    dep = table_to_mapper.get(fk.column.table)
  File "/usr/local/lib/python3.4/site-packages/sqlalchemy/util/langhelpers.py", line 754, in __get__
    obj.__dict__[self.__name__] = result = self.fget(obj)
  File "/usr/local/lib/python3.4/site-packages/sqlalchemy/sql/schema.py", line 1840, in column
    tablekey)
sqlalchemy.exc.NoReferencedTableError: Foreign key associated with column 'transactions.distributor_id' could not find table 'distributors' with which to generate a foreign key to target column 'id'