A simple bind with the old password should still work for some time...
This bug was referenced in samba master: 3625d1381592f7af8ec14715c6c2dfa4d9f02676 012bd9f5b780f7a90cf3bd918f044ea67fae7017 2ad44686229ba02f98de5769c26a3dfeaf5ada2b
This bug was referenced in samba v4-16-test: d92b46a4c04f2e2b30e60069404d0f4d31c2491e cafbb3e7307e0c1b1442ae02a8b83bb017a5eea9 64b2075c119e0cfa401082993f692bd48a343090
This bug was referenced in samba v4-14-test: 2472d44f9c93ab03bc0919bebc61b6874348001e f0891c0a8916dbddc422deb629557c51716d9064 1a0d92a9bef54a725266caec944f7882101a5a89
This bug was referenced in samba v4-15-test: 0da8b2b368321d57368424374bd9c8d0536900ac 0fcbfd39583e42354263018bb2b703413a781473 af30bd71cd33512fd78e686a9864d8fb3189c60c
This bug was referenced in samba v4-16-stable (Release samba-4.16.0): d92b46a4c04f2e2b30e60069404d0f4d31c2491e cafbb3e7307e0c1b1442ae02a8b83bb017a5eea9 64b2075c119e0cfa401082993f692bd48a343090
This bug was referenced in samba v4-14-stable (Release samba-4.14.13): 2472d44f9c93ab03bc0919bebc61b6874348001e f0891c0a8916dbddc422deb629557c51716d9064 1a0d92a9bef54a725266caec944f7882101a5a89
This bug was referenced in samba v4-15-stable (Release samba-4.15.7): 0da8b2b368321d57368424374bd9c8d0536900ac 0fcbfd39583e42354263018bb2b703413a781473 af30bd71cd33512fd78e686a9864d8fb3189c60c