STARTTLS style protocols, such as SMTP, have never had SSL2-only servers. TLS-stepup sockets should disable SSL2 v2-compatible helo messages (and SSL2).
Created attachment 30481 [details] [diff] [review] Proposed fix. Also renames useTLS to forTLSStepUp
r=javi, since PSM 2.0 gets built by default on nightly builds and I'm not sure if it's enabled on any of the tinderboxes, please build on at least Linux and windows before checking in. Actually, we probably need sr= now as well.
Fix checked in.
Verified per jgmyers' comments.