Dropped in a few delays in tests that (for me) remove consistently appearing

'test left threads behind' warnings. Tests in testZEO sometimes do
that too, but that's hard to reproduce.

src/ZEO/tests/ConnectionTests.py

@@ -299,6 +299,8 @@ class ConnectionTests(CommonSetupTearDown):
         # Stores should fail here
         self.assertRaises(ReadOnlyError, self._dostore)
         self._storage.close()
+        # Get rid of the 'test left new threads behind' warning
+        time.sleep(0.1)
 
     def checkReadOnlyFallbackWritable(self):
         # Open a fallback client to a read-write server; stores succeed

src/ZEO/tests/testAuth.py

@@ -66,9 +66,9 @@ class AuthTest(CommonSetupTearDown):
 
     def wait(self):
         for i in range(25):
+            time.sleep(0.1)
             if self._storage.test_connection:
                 return
-            time.sleep(0.1)
         self.fail("Timed out waiting for client to authenticate")
 
     def testOK(self):

src/ZEO/tests/testZEO.py

@@ -203,6 +203,7 @@ class MappingStorageTests(GenericTests):
 
     # XXX There are still a bunch of tests that fail.  Are there
     # still test classes in GenericTests that shouldn't be there?
+    # XXX Is the above comment still relevant?
 
 test_classes = [FileStorageTests, MappingStorageTests]