Calling (py:func <obj> <arg> ...) when <arg> is a list, fails

[oubiwann]

This can be duplicated with:

class Scratch:
    def __call__(self, x):
        return x

> (set callable (py:init 'lfe.scratch 'Scratch))
#($erlport.opaque python
  #B(128 2 99 108 ...))
> (py:func callable -9)
exception error: badarg
  in (: erlang atom_to_binary
       #($erlport.opaque python #B(128 2 99 108 102 101 46 115 99 114 ...))
       latin1)
  in (py func 4)

[oubiwann]

That last one did it.