https://github.com/linux-pam/linux-pam/commit/b0ec5d1e472a0cd74972bfe9575dcf6a3d0cad1c
So another way to solve this is "please upgrade to a recent version of linux-pam".
Thank you. Mike.
I just found that this bug has already been fixed in the upstream pam
code, 4 years ago.
