False positive py/uninitialized-local-variable

**Description of the false positive**

**Code samples or links to source code**

```python
class Foo:
def foo(self, a, b, c=0):
start = 0
visible = not (a == b and c)
end = start if visible else None
return end

```

CodeQL Version: 2.18.3

Alert : Local variable 'visible' may be used before it is initialized.

I suspect that the issue is caused by EssaVariable being unable to locate the assignment statement for the variable visible, but I'm not sure how to modify the ql statement.