What do you mean? We can only create an account [of the current version](https://mxr.mozilla.org/mozilla-central/source/mobile/android/base/fxa/authenticator/AndroidFxAccount.java#294) so we have to upgrade the pickle data before we create an account with it.

This means we can avoid storing the account version at all, and just upgrade based on pickle version, assuming we upgrade the pickle version each time we upgrade the account version.