should introduce an option to disable SNI, but as we're in feature freeze
  now I've addressed the obvious bug here (pointed out by Peter Sylvester): we
  shouldn't try to enable SNI when SSLv2 or SSLv3 is explicitly selected.
  Code for OpenSSL and GnuTLS was fixed. NSS doesn't seem to have a particular
  option for SNI, or are we simply not using it?