steps to reproduce:
1. Start the purchase flow for a paid app on marketplace-dev
2. Log in as a new user via Persona
3. Create PIN and click continue
4. In the confirm screen, close the screen by clicking "x"
5. Start the purchase flow again
User is back on the Create PIN
User is on the Confirm PIN screen. If a user returns after a month, we cannot expect the user to remember what they set as their PIN.
Let us not save the PIN until the user has confirmed it.
We save the PIN because we have to, but this will detect if they are coming back into the flow (from mkt) and remove their pin if they have a pin but haven't verified it.
I can still reproduce this on -dev. Same steps as comment 0
Fixed as part of another bug fix.