[1.2.X] Fixed #12475 -- Fixed an edge case with hidden fields in ModelAdmin...

[1.2.X] Fixed #12475 -- Fixed an edge case with hidden fields in ModelAdmin changelists when used in conjunction with list_display_links or list_editable. Thanks, Simon Meers, Julien Phalip, Karen and master.

Backport from trunk (r15722).

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.2.X@15724 bcc190cf-cafb-0310-a4f2-bffc1f526a37