Noted change in ftplib 1.68 closing SF patch 553277.
diff --git a/Misc/NEWS b/Misc/NEWS
index 5608af9..5998d0d 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -102,6 +102,13 @@
Library
+- ftplib.retrlines() now tests for callback is None rather than testing
+ for False. Was causing an error when given a callback object which
+ was callable but also returned len() as zero. The change may
+ create new breakage if the caller relied on the undocumented behavior
+ and called with callback set to [] or some other False value not
+ identical to None.
+
- random.gauss() uses a piece of hidden state used by nothing else,
and the .seed() and .whseed() methods failed to reset it. In other
words, setting the seed didn't completely determine the sequence of