If notifier is set in membership profile, on-behalf-of org name won't show up in email receipt

The main problem is that if you have a notifier set up, it ends up setting $email in CRM_Contribution_BAO_ContributionPage.php, function sendMail. This in turn causes $displayName never to get set, which I believe is what the email template uses to print the row about on-behalf-of info in the email.

I am not entirely sure the best way to patch this because I don't understand all the use cases involved.

A good way to test this is to create a membership profile with a notifier set, and then enable signup on behalf of an org.