fixed some changes

satella/__init__.py

-__version__ = '2.20.4a2'
+__version__ = '2.20.4a3'

satella/db.py

@@ -38,7 +38,9 @@ class transaction:
     @property
     def connection(self):
         if inspect.isfunction(self._connection):
-            return self._connection()
+            conn = self._connection()
+            self._connection = conn
+            return conn
         else:
             return self._connection