From a473b9da152d4cdd10eccc6d8eafa2b519da121d Mon Sep 17 00:00:00 2001
From: Raymond Hettinger <python@rcn.com>
Date: Sat, 28 Feb 2015 17:49:47 -0800
Subject: [PATCH] Use unsigned division and modulo for item assignment as well.

---
 Modules/_collectionsmodule.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/Modules/_collectionsmodule.c b/Modules/_collectionsmodule.c
index d12f0e8769e..908cfd2f3e1 100644
--- a/Modules/_collectionsmodule.c
+++ b/Modules/_collectionsmodule.c
@@ -780,7 +780,6 @@ deque_item(dequeobject *deque, Py_ssize_t i)
         b = deque->rightblock;
     } else {
         i += deque->leftindex;
-        assert(i >= 0);
         n = (Py_ssize_t)((unsigned) i / BLOCKLEN);
         i = (Py_ssize_t)((unsigned) i % BLOCKLEN);
         if (index < (Py_SIZE(deque) >> 1)) {
@@ -840,14 +839,16 @@ deque_ass_item(dequeobject *deque, Py_ssize_t i, PyObject *v)
         return deque_del_item(deque, i);
 
     i += deque->leftindex;
-    n = i / BLOCKLEN;
-    i %= BLOCKLEN;
+    n = (Py_ssize_t)((unsigned) i / BLOCKLEN);
+    i = (Py_ssize_t)((unsigned) i % BLOCKLEN);
     if (index <= halflen) {
         b = deque->leftblock;
         while (n--)
             b = b->rightlink;
     } else {
-        n = (deque->leftindex + len - 1) / BLOCKLEN - n;
+        n = (Py_ssize_t)(
+                ((unsigned)(deque->leftindex + Py_SIZE(deque) - 1))
+                / BLOCKLEN - n);
         b = deque->rightblock;
         while (n--)
             b = b->leftlink;