[AC-1066] Ti.Storekit uses incorrect log in

Using Ti.Storekit module, following instructions for "test validating receipts on iOS 7 and above" atop the accompanying app.js file, in "Sandbox" mode, created a "Test User" to test on device.. Problem: When creating a "Test User" it must be a non-existing iTunes account but "Sign In to iTunesStore" dialog that appears uses the device's actual iTunes account to log in. I've tried logging in with both the new Test User password (with non-Test User email) as well as the correct password for the email that appears in the dialog, both fail.