As mentioned in issue13672 currently there is no way to specify a 
qualname on types.FunctionType:

>>> def f():
...    def g():
...       pass
...    return g
... 
>>> g = f()
>>> g
<function f.<locals>.g at 0x7f1dac4d8ba0>
>>> types.FunctionType(f.__code__, {})
<function f at 0x7f1dac4dfae0>
>>> types.FunctionType(g.__code__, {})

If issue13672 is fixed, then the qualname can be derived from the passed
in code object like name is.  We can also add an optional parameter to
the FunctionType constructor for qualname.

I am working on a patch relative to the one I just posted for 
issue13672.

Note that #13672 refers to #12857.