Fixed redundant definition of `connection_created` signal due to DVCS mistake. My bad.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@10187 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/db/backends/signals.py

 from django.dispatch import Signal
 
 connection_created = Signal()
-from django.dispatch import Signal
-
-connection_created = Signal()