pam_rundir does not work with util-linux-login

for some reason, logging in with util-linux-login installed does not properly set up XDG_RUNTIME_DIR, with a
session required pam_rundir.so in /etc/pam.d/base-session
shadow-login instead works fine- both of them provide a /bin/login linked against libpam.so/libpam_misc.so

i can reproduce this in a alpine:edge container too- adding that line to base-session and trying login with either installed has the runtime dir set only for shadow-login. not sure why this is the case