diff --git a/mercurial/branchmap.py b/mercurial/branchmap.py
index 6578654916ae640bd0e28b03e27eb8740c0bcc85_bWVyY3VyaWFsL2JyYW5jaG1hcC5weQ==..7c9d4cf23adfe26ac4987ed329fe94a8166e0f70_bWVyY3VyaWFsL2JyYW5jaG1hcC5weQ== 100644
--- a/mercurial/branchmap.py
+++ b/mercurial/branchmap.py
@@ -319,7 +319,6 @@
         return self._branchtip(self[branch])[0]
 
     def iteropen(self, nodes):
-        self._verifyclosed()
         return (n for n in nodes if n not in self._closednodes)
 
     def branchheads(self, branch, closed=False):