Purchasing a siteless license from Jetpack.com leads to malformed URL and the license does not show up

Post-checkout, I am redirected to this URL:
https://wordpress.com/checkout/jetpack/thank-you/licensing-manual-activate-license-key/jetpack_security_t1_yearly?receiptId=%3AreceiptId

Note the last part - `%3AreceiptId` instead of an actual receipt id value.


Steps to reproduce:
1. Open up an incognito session to make sure you are not logged in anywhere.
2. Go to jetpack.com/pricing
3. Pick any Jetpack product.
4. Go through the checkout steps
5. You should now be at a login screen which asks you for your email - after you enter it, you should get a login link in your inbox.
6. Following the login link, you will be presented with the screenshot seen above - a success screen but with a license field that does not load because of the faulty receipt id.

Trace the checkout flow from Jetpack pricing through the login-link callback and the thank-you URL construction. Reproduce the siteless purchase and inspect how the receipt ID is inserted; done means the redirect contains the actual receipt ID and the license appears on the success screen.

Written by the indexing model from the issue text.