Wrong field assigned in views_handler_relationship.inc

I'm not quite shure, if this is a bug, or if i'm doing something wrong.

In have a module that implements hook_views_data.
In hook_views_data i create a relationship:
In most examples the fields with the relation have unique names.
In my case this is not possible. This is how i define the relationship.

 $data['sishandball_spiele']['mannschaft_1_id'] = array(
    'title' => t('Mannschaft 1 ID'), 
    'help' => t('Mannschaft 1 ID help'),
    'relationship' => array(
      'base' => 'sishandball_mannschaften', 
      'field' => 'mannschaft_id', 
      'handler' => 'views_handler_relationship', 
      'label' => t('SIS Handball Mannschaft 1'),
    ),

When i add the relationship i get the follwing error:

Column not found: 1054 Unknown column 'sishandball_spiele.mannschaft_id' in 'on clause

This is the query created by views:

SELECT sishandball_spiele.datum AS sishandball_spiele_datum
FROM 
{sishandball_spiele} sishandball_spiele
INNER JOIN {sishandball_mannschaften} sishandball_mannschaften_sishandball_spiele ON sishandball_spiele.mannschaft_id = sishandball_mannschaften_sishandball_spiele.mannschaft_id

As you can see the name mannschaft_1_id does not appear in the ON statement

If i change the line no 117 in views_handler_relationship.inc
from

$def['left_field'] = $this->real_field;

to

$def['left_field'] = $this->field

everything is working fine.