Identity is not the same thing as equality in Python (#1306)

Use ==/!= to compare str, bytes, and int literals: __fmt is not 'raw'__ --> __fmt != 'raw'__

$ __python__
```python
>>> raw = 'ra'
>>> raw += 'w'
>>> raw
'raw'
>>> raw == 'raw'
True
>>> raw is 'raw'
False
```

pwnlib/commandline/scramble.py

@@ -101,7 +101,7 @@ def main(args):
     else:
         args.output.write(formatters[fmt[0]](output))
 
-    if tty and fmt is not 'raw':
+    if tty and fmt != 'raw':
         args.output.write('\n')