diff --git a/mercurial/revset.py b/mercurial/revset.py
--- a/mercurial/revset.py
+++ b/mercurial/revset.py
@@ -2804,7 +2804,7 @@ class generatorset(abstractsmartset):
                 pass
             return self.first()
         if self:
-            return it.next()
+            return it().next()
         return None
 
     def last(self):
@@ -2818,7 +2818,7 @@ class generatorset(abstractsmartset):
                 pass
             return self.first()
         if self:
-            return it.next()
+            return it().next()
         return None
 
 def spanset(repo, start=None, end=None):
diff --git a/tests/test-issue619.t b/tests/test-issue619.t
--- a/tests/test-issue619.t
+++ b/tests/test-issue619.t
@@ -28,3 +28,9 @@ Bogus fast-forward should fail:
   abort: merging with a working directory ancestor has no effect
   [255]
 
+Even with strange revset (issue4465)
+
+  $ hg merge ::.
+  abort: merging with a working directory ancestor has no effect
+  [255]
+