[1.2.X] Fixed #13126 -- Ensured that individual form errors are displayed when...

[1.2.X] Fixed #13126 -- Ensured that individual form errors are displayed when errors occur on a list-editable changelist. Thanks to slafs for the report, and to Julien Phalip for the patch.

Backport of r15580 from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.2.X@15581 bcc190cf-cafb-0310-a4f2-bffc1f526a37