Found this while working on #10892.

Expected behavior

After rotating the device, all text field values ​​should be retained.

Actual behavior

After rotating the device, only the password field value is retained, while the other two are lost (display name and username).

Steps to reproduce the behavior

1. Make sure you have OAuth credentials with user creation capabilities.
2. If you have logged in to the app, sign out.
3. On the initial screen, tap Sign up for WordPress.com.
4. Tap Sign up with email.
5. Enter an email address that is not associated with a WordPress.com account.
6. On the next screen, tap Open mail.
7. On the signup email sent to the address used in step 5, tap Sign up to WordPress.com.
8. On the epilogue screen, fill in the Display Name, Username and Password fields with different values and rotate the device.
9. Notice that both the Display Name and Username fields have not retained their values.

Tested on Emulator (Pixel 2), Android 9, WPAndroid 13.7-rc-1