# HG changeset patch
# User Yuya Nishihara <yuya@tcha.org>
# Date 2019-06-09 13:18:22
# Node ID d279e4f453c4b3d05b70df0c1d2c2cf0046a45fc
# Parent  aae93201f75888deac664d16e01af3c4bc76ac22

revset: use nullrev constant in merge()

diff --git a/mercurial/revset.py b/mercurial/revset.py
--- a/mercurial/revset.py
+++ b/mercurial/revset.py
@@ -1361,7 +1361,8 @@ def merge(repo, subset, x):
     # i18n: "merge" is a keyword
     getargs(x, 0, 0, _("merge takes no arguments"))
     cl = repo.changelog
-    return subset.filter(lambda r: cl.parentrevs(r)[1] != -1,
+    nullrev = node.nullrev
+    return subset.filter(lambda r: cl.parentrevs(r)[1] != nullrev,
                          condrepr='<merge>')
 
 @predicate('branchpoint()', safe=True)