[1.0.X] Fixed #10585: comment redirects built from the `next` parameter now...

[1.0.X] Fixed #10585: comment redirects built from the `next` parameter now work correctly when `next` already contains a query string. Backport of r10424 from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.0.X@10425 bcc190cf-cafb-0310-a4f2-bffc1f526a37