Only refill readline history if it doesn't look like it's been changed.

IPython/core/interactiveshell.py

@@ -139,14 +139,24 @@ def __init__(self, shell):
         self._nested_level = 0
 
     def __enter__(self):
+        if self._nested_level == 0:
+            self.readline_tail = self.get_readline_tail()
         self._nested_level += 1
 
     def __exit__(self, type, value, traceback):
         self._nested_level -= 1
         if self._nested_level == 0:
-            self.shell.refill_readline_hist()
+            if self.get_readline_tail() != self.readline_tail:
+                self.shell.refill_readline_hist()
         # Returning False will cause exceptions to propagate
         return False
+
+    def get_readline_tail(self, n=10):
+        """Get the last n items in readline history."""
+        end = self.shell.readline.get_current_history_length() + 1
+        start = max(end-n, 1)
+        ghi = self.shell.readline.get_history_item
+        return [ghi(x) for x in range(start, end)]
 
 
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