From 92f8e925c2ade5c81fd9d4a9b83a84dfd9a7097e Mon Sep 17 00:00:00 2001
From: Sebastian Thiel <byronimo@gmail.com>
Date: Fri, 30 Jan 2015 05:28:21 +0100
Subject: [PATCH] Added assertion in spot that might help tracking down the
 issue when it happens

[skip ci]
---
 smmap/mman.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/smmap/mman.py b/smmap/mman.py
index 7180c75..975fafa 100644
--- a/smmap/mman.py
+++ b/smmap/mman.py
@@ -131,6 +131,7 @@ def use_region(self, offset=0, size=0, flags=0):
         # END need region handling
 
         self._ofs = offset - self._region._b
+        assert(self._ofs > -1)
         self._size = min(size, self._region.ofs_end() - offset)
 
         return self