SQL statement with trailing comment stalls in interactive session

## Problem

When running this command in an interactive session, it stalls, and will probably not get to submitted to the database at all. I think the shell thinks the context is not finished yet.
```
$ crash
CONNECT OK
cr> select 42; -- foo
```

On the other hand, when submitting the command non-interactively, it works well.
```sql
$ crash -c 'select 42; -- foo'
CONNECT OK
+----+
| 42 |
+----+
| 42 |
+----+
SELECT 1 row in set (0.001 sec)
```