Fix test_export_invalid with certain versions of OpenSSL.  Previously OpenSSL did the NULL check for us, now we do it.
diff --git a/OpenSSL/crypto/crl.c b/OpenSSL/crypto/crl.c
index 614a606..543708e 100644
--- a/OpenSSL/crypto/crl.c
+++ b/OpenSSL/crypto/crl.c
@@ -138,6 +138,16 @@
         return NULL;
     }
 
+    /* Some versions of OpenSSL check for this, but more recent versions seem
+     * not to.
+     */
+    if (!key->pkey->ameth) {
+        PyErr_SetString(
+            crypto_Error, "Cannot export with an unitialized key");
+        return NULL;
+    }
+
+
     bio = BIO_new(BIO_s_mem());
     tmptm = ASN1_TIME_new();
     if (!tmptm) {