@jedp - I'd rather do what @seanmonstar suggests here.

These are the places where it matters:

```
./misc/helpers.js:    user.getAssertion(email, user.getOrigin(), function(assert) {
./misc/internal_api.js:        user.getAssertion(email, user.getOrigin(), function(assertion) {
./user.js:              User.getAssertion(email, "https://login.persona.org", function(assertion) {
./user.js:                  User.getAssertion(email, audience, onComplete, onFailure);
./user.js:              User.getAssertion(email, audience, onComplete, onFailure);
./user.js:          User.getAssertion(loggedInEmail, origin,
```

Or, easier yet, you could follow the approach in:
https://github.com/mozilla/browserid/pull/3654/files#r5158662