Importing the Django test client is somewhat expensive, and we only
use it within one view function that's not used in production. So
there's a significant startup-time performance optimization in doing
an import inside the view code.
This often can cause minor caching problems.
Obviously, it'd be better if we had access to the AST and thus could
do this rule for UserProfile objects in general.
Seems like the more logical check. Also, the previous code makes it feel
like there is a potential vulnerability where one could get an email change
object in a realm where email changes are disabled, and then open that link
while logged in to a different realm.
While we're at it, remove the unnecessary check that the user is
logged in when clicking the confirmation link; that creates
unnecessary trouble for users who use multiple browsers.
