# HG changeset patch
# User Valentin Gatien-Baron <vgatien-baron@janestreet.com>
# Date 2019-01-21 21:37:30
# Node ID 465f2d0df9ae1f36e18fd42e33317a1e38e2f602
# Parent  6e9ba867a9461adcca7b08d5479ae5f74d1473d2

deltas: accept and skip None return for delta info

They are some extra computation that will shortcut the delta compression if the
delta seems hopeless, returning None.

diff --git a/mercurial/revlogutils/deltas.py b/mercurial/revlogutils/deltas.py
--- a/mercurial/revlogutils/deltas.py
+++ b/mercurial/revlogutils/deltas.py
@@ -1025,8 +1025,9 @@ class deltacomputer(object):
                 nominateddeltas.append(deltainfo)
             for candidaterev in candidaterevs:
                 candidatedelta = self._builddeltainfo(revinfo, candidaterev, fh)
-                if isgooddeltainfo(self.revlog, candidatedelta, revinfo):
-                    nominateddeltas.append(candidatedelta)
+                if candidatedelta is not None:
+                    if isgooddeltainfo(self.revlog, candidatedelta, revinfo):
+                        nominateddeltas.append(candidatedelta)
             if nominateddeltas:
                 deltainfo = min(nominateddeltas, key=lambda x: x.deltalen)
             if deltainfo is not None: