[1.2.X] Fixed #14126 -- Fixed an issue with changes to the blocktrans tag...

[1.2.X] Fixed #14126 -- Fixed an issue with changes to the blocktrans tag introduced in r13973 related to multiple plural forms. Thanks, mark0978, svetlyak40wt and Ramiro.

Backport from trunk (r14239).

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.2.X@14240 bcc190cf-cafb-0310-a4f2-bffc1f526a37