[m-users.] 'help' in debugger shows nothing

[Harrison Pincket]

Hello,

I am using ROTD 2019-05-13 which I installed with the --disable-most-
grades option. I am trying to learn my way around the debugger so I
wrote a simple predicate to compute the nth Fibonacci number. It
compiles and works fine.

But when I run the following:
```
$ mmc -s asm_fast.gc.debug.stseg fib
$ mdb ./fib
mdb> help
```

The `help` command generates no output. This is either a bug or I am
invoking it incorrectly. Though if I enter nonsense the debugger asks
me to enter the `help` command. The `break` command appears to work
fine.

Thanks,
Harrison