PS1 is _supposed to be unset_ when the shell is non-interactive.  Since 5.2
and perhaps before that, the redhat default environment has gone to great
lengths to break this behavior.  (so much for peer review.)

here's my repair script which does roughly what needs to be done...
{modify the export line to not export PS1 or INPUTRC to be 100% correct}

report() { echo "$@" 1>&2 ; }

if egrep -qs ^INPUTRC= /etc/profile; then
  report "fixing /etc/profile and creating /etc/skel/.inputrc"
  perl -pi~ -e 's,^(INPUTRC=),# $1,' /etc/profile
  echo '$include /etc/inputrc' >/etc/skel/.inputrc
fi

if egrep -qs ^PS1= /etc/profile; then
  report "don't unconditionally set PS1 in /etc/profile !!!!"
  perl -pi~ -e 's,^(PS1=),test "\$PS1" && $1,' /etc/profile /etc/bashrc
fi