Resolves a test failure on 32-bit platforms.

https://github.com/pyca/pyopenssl/issues/657

Patch copied from upstream source repository:

https://github.com/pyca/pyopenssl/commit/ecc0325479c0d5c5f2ca88b4550e87cdb59d6c95

From ecc0325479c0d5c5f2ca88b4550e87cdb59d6c95 Mon Sep 17 00:00:00 2001
From: Alex Gaynor <alex.gaynor@gmail.com>
Date: Thu, 6 Jul 2017 22:14:44 -0400
Subject: [PATCH] Fixed #657 -- handle OverflowErrors on large allocation
 requests

---
 tests/test_rand.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/tests/test_rand.py b/tests/test_rand.py
index bdd3af08..6adf72a1 100644
--- a/tests/test_rand.py
+++ b/tests/test_rand.py
@@ -32,10 +32,10 @@ def test_bytes_wrong_args(self, args):
 
     def test_insufficient_memory(self):
         """
-        `OpenSSL.rand.bytes` raises `MemoryError` if more bytes are requested
-        than will fit in memory.
+        `OpenSSL.rand.bytes` raises `MemoryError` or `OverflowError` if more
+        bytes are requested than will fit in memory.
         """
-        with pytest.raises(MemoryError):
+        with pytest.raises((MemoryError, OverflowError)):
             rand.bytes(sys.maxsize)
 
     def test_bytes(self):