[1.2.X] Fixed #13433 -- Changed default behavior of Django email message...

[1.2.X] Fixed #13433 -- Changed default behavior of Django email message wrappers to not mangle lines starting with 'From '. Thanks Leo for the report and patch.

Backport of [15669] from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.2.X@15670 bcc190cf-cafb-0310-a4f2-bffc1f526a37