Fixed #7683: Try not to delete uploaded files before moving them, and don't...

Fixed #7683: Try not to delete uploaded files before moving them, and don't wig out of someone else does. Patch from screeley and spaetz.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@8217 bcc190cf-cafb-0310-a4f2-bffc1f526a37