ForeignKeyRawIdWidget turns string into comma-separated chars in lookup URL

[andyhd]

Using a ForeignKey with limit_choices_to a filter that matches a string:

class Foo(models.Model):
    bar = models.ForeignKey('Bar', limit_choices_to={'blarch': 'quux'})
#                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
class Bar(models.Model):
    blarch = models.CharField(max_length=20)

And a custom admin with raw_id_fields:

class FooAdmin(admin.ModelAdmin):
    raw_id_fields = ('bar',)

results in the changeform magnifying glass lookup link having a URL like this:
"../../../fail/blarch/?blarch=q,u,u,x"

Fixed by placing the single string value in a list (see patch)

[Karen Tracey]

Looks like James fixed this with a slightly different patch in r9533/r9534.