diff -r 3c7c13e75663 -r f290f130d7fc mercurial/fileset.py
--- a/mercurial/fileset.py	Sat Mar 31 23:31:28 2018 -0700
+++ b/mercurial/fileset.py	Sat Mar 31 23:26:07 2018 -0700
@@ -513,9 +513,7 @@
     revspec = getstring(r, reverr)
     if not revspec:
         raise error.ParseError(reverr)
-    basenode, node = scmutil.revpairnodes(repo, [baserevspec, revspec])
-    basectx = repo[basenode]
-    ctx = repo[node]
+    basectx, ctx = scmutil.revpair(repo, [baserevspec, revspec])
     return getset(mctx.switch(ctx, _buildstatus(ctx, x, basectx=basectx)), x)
 
 @predicate('subrepo([pattern])')