Report global object redefinition

[sam-s]

Current problem

The following code redefines global objects and should be reported as such:

foo = 10
def f(x):
    return x + foo
foo = 100
def f(x):
    return x - foo

Desired solution

It would be nice to get a warning like

line 4: global variable `foo` redefined (defined in line 1)
line 5: global function `f` redefined (defined in line 2)

Additional context

We already have redefined-outer-name but it only warns when a global name is redefined locally, not globally.