More tests tweaks

Named cursors on old server versions have a different prefetch behaviour.
This has hidden me the supported range of the 24:00 time format.
Let's have another go at full testing...

tests/test_dates.py

@@ -309,7 +309,7 @@ class DatetimeTests(ConnectingTestCase, CommonDatetimeTestsMixin):
         from datetime import timedelta
         self._test_type_roundtrip_array(timedelta(seconds=30))
 
-    @skip_before_postgres(8, 4)
+    @skip_before_postgres(8, 1)
     def test_time_24(self):
         from datetime import time
 

tests/test_with.py

@@ -207,6 +207,7 @@ class WithCursorTestCase(WithTestCase):
             with self.conn as conn:
                 with conn.cursor('named') as cur:
                     cur.execute("select 1/0")
+                    cur.fetchone()
         except psycopg2.DataError, e:
             self.assertEqual(e.pgcode, '22012')
         else: