"Always subscribe me to mailing lists" does not work everytime

[Andrea Corbellini]

Steps to reproduce:
1. Set "Always subscribe me to mailing lists" in your +editemails
2. Ask a team administrator to add you as a member of a team

What happens:
You become a member of the team, but you are not subscribed to the mailing list.

[Curtis Hovey (sinzui)]

mailing_list_auto_subscribe_policy rules are explicitly disabled when joining a restricted or moderated team. While this is clear in the code, There is not other documentation about this. The rules are only enforced in the browser--the policy is always ignored when users are subscribed over API.

I think this is wrong. A better implmentation is to /subcribe/ a function for mailing_list_auto_subscribe_policy to the team join event. There is not event though :( We want membership status changes to emit an event that functions can subscribe to. I think the odd rules are caused by the delay in setting the TeamMembship status to approved. If something could watch the status change to approved, subscriptions would be honoured on the api and the browser. (we could also defer sending email notifications too)