execution flows will use the same DH primes (currently
exim.dev.20160529.3).
-JH/25 OpenSSL: Fix beck-compatibiility behaviour surrounding tls_certificates
+JH/25 OpenSSL: Fix back-compatibiility behaviour surrounding tls_certificates
option in smtp transport, to match the documentation. Previously
verification was not being done in some cases where it should have been.