# HG changeset patch
# User Pierre-Yves David <pierre-yves.david@fb.com>
# Date 2015-09-23 07:41:07
# Node ID 428a8747f4eeabe36efc411d216bbe0e39faae12
# Parent  d157e1f18e3f529006217e1584edeec1d9288485

revset: avoid implicit None testing in revset

Implicit None testing is a very good way to get in trouble. We explicitly test
for None.

diff --git a/mercurial/revset.py b/mercurial/revset.py
--- a/mercurial/revset.py
+++ b/mercurial/revset.py
@@ -3225,10 +3225,13 @@ class filteredset(abstractsmartset):
         return lambda: self._iterfilter(it())
 
     def __nonzero__(self):
-        it = self
-        fast = self.fastasc or self.fastdesc
-        if fast:
+        fast = self.fastasc
+        if fast is None:
+            fast = self.fastdesc
+        if fast is not None:
             it = fast()
+        else:
+            it = self
 
         for r in it:
             return True