Let OpenSSL choose the digest if digest for Openssl::OCSP::Request#sign is nil.

Author: jackorp

ext/openssl/ossl_ocsp.c

@@ -382,7 +382,7 @@ ossl_ocspreq_sign(int argc, VALUE *argv, VALUE self)
     if (!NIL_P(flags))
 	flg = NUM2INT(flags);
     if (NIL_P(digest))
-	md = EVP_sha1();
+	md = NULL;
     else
 	md = ossl_evp_get_digestbyname(digest);
     if (NIL_P(certs))