The new logic in get_trust_credentials() in winbindd_cm.c is wrong for one way outgoing trusts.
This code is not backported to v4-2-test, I'll retest this with v4-2-test, but this is no blocker for 4.2.0rc3...
I guess it's fixed with 064d40f4d30d711797b76082afbb936dcfd9c659.