AC_SUB bup_make "$MAKE"
-bup_python="$PYTHON"
+bup_python="$(type -p "$PYTHON")"
test -z "$bup_python" && bup_python="$(bup_find_prog python2.7 '')"
test -z "$bup_python" && bup_python="$(bup_find_prog python2.6 '')"
test -z "$bup_python" && bup_python="$(bup_find_prog python2 '')"