# HG changeset patch
# User Augie Fackler <augie@google.com>
# Date 1500910191 14400
# Node ID 888f24810ea2eecfa78bccad9506e21dd8da4ba3
# Parent  672ad4f3bb84cb8163744b463de7b705b8c2688f
obsutil: defend against succsmarkers() returning None

I'm not sure if this is a realistic problem, but doing this avoids
some pretty awful test failures on Python 3, and it looks like it
should be harmless.

Differential Revision: https://phab.mercurial-scm.org/D274

diff -r 672ad4f3bb84 -r 888f24810ea2 mercurial/obsutil.py
--- a/mercurial/obsutil.py	Mon Jul 24 11:28:59 2017 -0400
+++ b/mercurial/obsutil.py	Mon Jul 24 11:29:51 2017 -0400
@@ -307,7 +307,7 @@
         seenrevs.add(rev)
         if phase(repo, rev) == public:
             continue
-        if set(succsmarkers(node)).issubset(addedmarkers):
+        if set(succsmarkers(node) or []).issubset(addedmarkers):
             obsoleted.add(rev)
     return obsoleted