OG context lost for nodereference autocomplete

Hi,

there seems to be a potential bug where og_user_roles cannot pick up the group context for AJAXy operations such as nodereference autocomplete.

Steps to reproduce:
- create a new user role "Group Editor"
- add a nodereference field to content type A (any will do)
- change the permissions so that only Group Editors can create content type A node and view/edit the nodereference field
- create a new user
- create a group that can have the "Group Editor" role
- add the new user to the group and assign it the "Group Editor" role within the group.
- log in with the new user and go to /node/add/content_type_a
- start typing the title of an existing node in the nodereference field.

Even if the node edit path has ?gids[]=GID, the access check in /nodereference/autocomplete does not pick up the context.