From 898cf85c25de57a0c40bd9bedc00519674d09457 Mon Sep 17 00:00:00 2001
From: Tim Peters <tim.peters@gmail.com>
Date: Wed, 13 Jun 2001 20:50:08 +0000
Subject: [PATCH] _PyLong_AsByteArray:  added assert that the input is
 normalized.  This is outside the function's control, but is crucial to
 correct operation.

---
 Objects/longobject.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/Objects/longobject.c b/Objects/longobject.c
index 3c22470fb0d..f8a912940a9 100644
--- a/Objects/longobject.c
+++ b/Objects/longobject.c
@@ -358,7 +358,11 @@ _PyLong_AsByteArray(PyLongObject* v,
 		pincr = -1;
 	}
 
-	/* Copy over all the Python digits. */
+	/* Copy over all the Python digits.
+	   It's crucial that every Python digit except for the MSD contribute
+	   exactly SHIFT bits to the total, so first assert that the long is
+	   normalized. */
+	assert(ndigits == 0 || v->ob_digit[ndigits - 1] != 0);
 	j = 0;
 	accum = 0;
 	accumbits = 0;