From 32dffaa0164761fb94cffa32cfe01b3d0a83bf18 Mon Sep 17 00:00:00 2001
From: Guido van Rossum <guido@python.org>
Date: Tue, 24 Dec 1991 13:27:34 +0000
Subject: Fix assignment of a list to a slice of itself.

---
 Objects/listobject.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/Objects/listobject.c b/Objects/listobject.c
index 2e2b9a2..5811f40 100644
--- a/Objects/listobject.c
+++ b/Objects/listobject.c
@@ -357,8 +357,17 @@ list_ass_slice(a, ilow, ihigh, v)
 #define b ((listobject *)v)
 	if (v == NULL)
 		n = 0;
-	else if (is_listobject(v))
+	else if (is_listobject(v)) {
 		n = b->ob_size;
+		if (a == b) {
+			/* Special case "a[i:j] = a" -- copy b first */
+			int ret;
+			v = list_slice(b, 0, n);
+			ret = list_ass_slice(a, ilow, ihigh, v);
+			DECREF(v);
+			return ret;
+		}
+	}
 	else {
 		err_badarg();
 		return -1;
-- 
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