The Readline library for Tcl (tclreadline) enables history
substitutions, which means that lines that begin with `^` or `!` are
preprocessed by readline. This interferes with some step1 tests of the
`^` form (--> with-meta).
Now the Tcl implementation supports a `--raw` command line flag which
disables the readline library and opts for simple input from stdin. The
tests (Makefile) are run with `--raw`.
