Detect `unittest.fail()` calls for assignment warning

[Flamefire]

Current problem

See this example

from unittest import TestCase
import os

class TestX(TestCase):
  def test_foo(self):
    if 'FOO' in os.environ:
        x = 1
    else:
        self.fail()
    print(x) # E0606:possibly-used-before-assignment

Although there is no way to reach the last line without x being unassigned it is reported as such.

Desired solution

self.fail() should be detected as terminating similar to raise ...

Additional context

No response