False-positive UselessAssignment when in a slim capture block

[jhubert]

This is a simple recreation of the issue I bumped into with a form_for helper in rails. I'm using capture so that it's distilled down to the essence of the issue:

- url = 'https://google.com'
= capture do
  a href=url = 'Google'

Running slim-lint on this gives me:

test.html.slim:2 [W] RuboCop: Useless assignment to variable - `url`.

[seliverstov-maxim]

up

[yjukaku]

I believe this happens with any method that takes a block, not just capture.

[jclusso]

Any idea on how to fix this. Happy to open a PR with some guidance.