Repl panics with capital variables

[B-Teague]

I accidentally had caps lock on which causes the repl to panic.

Enter an expression to evaluate, or a definition (like x = 1) to use later. » X=1 panicked at 'not yet implemented: handle pattern other than identifier (which repl doesn't support)', crates/repl_ui/src/repl_state.rs:123:25