mdw/build: Keep track of the original source directory in `$toppath'.

[profile] / bin / run-with-shell-env

#! /bin/bash -x
exec >/tmp/mdw/hacky.log 2>&1
case ${__mdw_profile+t} in
  t) ;;
  *)
    __mdw_force_secure_session=yes
    export SHELL=/bin/bash USER=$(/bin/id -un)
    set +x
    . $HOME/.bash_profile
    set -x
    ;;
esac
exec "$@"