LDAP password screen displayed when login passwordless with non-LDAP email

[rleitan]

STR:

1. Login passwordless and create an account in Mozillians staging (e.g. [email protected])
2. Go to Settings-Add identity and add an LDAP email (e.g. [email protected])
3. Log out
4. Log in using the LDAP email from step 2 then log out
5. Click Log in button and enter the yahoo email (passwordless) then click Enter button

[Expected results]:
Passwordless login flow should be displayed

[Actual result]:
LDAP password screen is displayed

[Note]:
The issue is reproducible even on a new Firefox clean profile

[viorelaioia-zz]

I encountered same issue by following the next scenario:
Ratcheting (linking rule disabled):
Mozillians account with 2 identities: Github 2fa + fxa 2fa, email [email protected]

Deratcheting (linking rule enabled):
Login with github 2fa for the first time => linking happens (fxa profile with 2 identities: github and fxa)
Logout
Entering email [email protected] in nlx email screen returns LDAP password screen instead of "send email" screen.

More info:
Person API returns \"connection_method\": \"ad\" for both email addresses:
https://person-api.sso.allizom.org/v1/connection/[email protected]
https://person-api.sso.allizom.org/v1/connection/[email protected]

We don't have a consistent way of reproducing this issue, but we were able to reproduce it once by following the above scenarios.