Bug in compose introduced in 0.10.0

Consider a file temp.py :

import toolz
import functools

print("toolz:", toolz.__version__)

def g(x):
    return x

class A(object):

    def __call__(self):

        _fg = toolz.compose(lambda x:x, g)

        class Inner(object):
            fg = _fg
        return Inner()
    
a = A()()
print(a.fg(2))

with toolz 0.9.0:

$ python temp.py
toolz: 0.9.0
2

With toolz 0.10.0:

$ python temp.py
toolz: 0.10.0
Traceback (most recent call last):
  File "temp.py", line 21, in <module>
    print(a.fg(2))
  File "/Users/Thomas/.local/miniconda3/envs/mantik_dev/lib/python3.7/site-packages/toolz/functoolz.py", line 486, in __call__
    ret = self.first(*args, **kwargs)
TypeError: g() takes 1 positional argument but 2 were given

In the second example, g gets called with an additional <__main__.A.__call__.<locals>.Inner object as first argument.

If not a bug, it's at least a change of behavior breaking code using toolz.

The above example is very reduced and may look strange but is totally sensible in the usecase where it's actually used.

Start by running the reduced reproduction in temp.py with the affected toolz versions, then inspect toolz/functoolz.py around line 486 where the traceback enters call. Done means the composition no longer passes the Inner instance as an extra argument and the reproduction prints 2 without an exception.