set_input from filestream causes panic

[jasonhemann]

I don't believe this is expected behavior.

[jhemann] 14:51:06$ export RUST_BACKTRACE=full; scryer-prolog
?- open("/Users/jhemann/temp.txt", read, S), set_input(S).
   S = '$stream'(0x600000182410).
thread 'main' panicked at src/machine/machine_state.rs:699:9:
internal error: entered unreachable code: Stream must be a Stream::Readline(_)
stack backtrace:
   0:        0x1051df6b6 - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::h0fd572ca60ee9a4e
   1:        0x104cde6e3 - core::fmt::write::hbc078725bba6692a
   2:        0x1051acfb2 - std::io::Write::write_fmt::h100f2ae009a3df53
   3:        0x1051e3782 - std::sys::backtrace::BacktraceLock::print::hf0d5a155265a9dd5
   4:        0x1051e35d5 - std::panicking::default_hook::{{closure}}::h5499fb85b118791b
   5:        0x1051e3e59 - std::panicking::rust_panic_with_hook::h10014b4a7f4c072b
   6:        0x1051e3825 - std::panicking::begin_panic_handler::{{closure}}::hc871510d12acad65
   7:        0x1051e37b9 - std::sys::backtrace::__rust_end_short_backtrace::hca0d49bc0c1e56d3
   8:        0x1051e37ac - _rust_begin_unwind
   9:        0x10526543f - core::panicking::panic_fmt::haa8e13f18984c8e5
  10:        0x104fae877 - scryer_prolog::machine::machine_state::MachineState::read_term_from_user_input::hba5c1dd14b15da16
  11:        0x104f0a1a9 - scryer_prolog::machine::Machine::run_module_predicate::hc8e99b550e72289e
  12:        0x105147d81 - scryer_prolog::run_binary::h32a5b68e7ed4a990
  13:        0x104ccee06 - std::sys::backtrace::__rust_begin_short_backtrace::hb012d8fe91153c41
  14:        0x104ccf1db - _main
[jhemann] 14:51:08$ scryer-prolog --version
v0.9.4-210-gff034326-modified