sslutil: remove "strict" argument from validatesocket() It was only used by mail.py as part of processing smtp.verifycert, which was just removed.

mail: unsupport smtp.verifycert (BC) smtp.verifycert was accidentally broken by cca59ef27e60. And, I believe the "loose" value has been broken for longer than that. The current code refuses to talk to a remote server unless the CA is trusted or the fingerprint is validated. In other words, we lost the ability for smtp.verifycert to lower/disable security. There are special considerations for smtp.verifycert in sslutil.validatesocket() (the "strict" argument). This violates the direction sslutil is evolving towards, which has all security options determined at wrapsocket() time and a unified code path and configs for determining security options. Since smtp.verifycert is broken and since we'll soon have new security defaults and new mechanisms for controlling host security, this patch formally deprecates smtp.verifycert. With this patch, the socket security code in mail.py now effectively mirrors code in url.py and other places we're doing socket security. For the record, removing smtp.verifycert because it was accidentally broken is a poor excuse to remove it. However, I would have done this anyway because smtp.verifycert is a one-off likely used by few people (users of the patchbomb extension) and I don't think the existence of this seldom-used one-off in security code can be justified, especially when you consider that better mechanisms are right around the corner.

update: fix bare --clean to work on new branch (issue5003) (BC) Before this commit bare update --clean on newly created branch updates to the parent commit, even if there are later commits on the parent commit's branch. Update to the latest head on the parent commit's branch instead. This seems reasonable as clean should discard uncommited changes, branch is one of them.