--- cryptography-1.5.2/src/cryptography/hazmat/backends/__init__.py.orig	2016-10-17 12:23:32.705257213 +0200
+++ cryptography-1.5.2/src/cryptography/hazmat/backends/__init__.py	2016-10-17 12:23:48.238260931 +0200
@@ -29,6 +29,23 @@
             )
         ]
 
+    if _available_backends_list is None or len(_available_backends_list) == 0:
+        # backend 1
+        try:
+            from cryptography.hazmat.backends.commoncrypto.backend import backend as be_cc
+        except ImportError:
+            be_cc = None
+        # backend 2
+        try:
+            from cryptography.hazmat.backends.openssl.backend import backend as be_ossl
+        except ImportError:
+            be_ossl = None
+        # add any backends of your own
+
+        _available_backends_list = [
+            be for be in (be_cc, be_ossl) if be is not None
+        ]
+
     return _available_backends_list
 
 _default_backend = None