Improve suggesting Performance/RedundantMerge

[wscourge]

Is your feature request related to a problem? Please describe.

Performance/RedundantMerge, that's unsafe-autocorrectable, suggests that I should:

Use accumulator[:low] = true instead of accumulator.merge!(low => true).

on the code below:

[{ a: 1 }, { a: 2 }, { a: 3 }].reduce({}).each do |accumulator, current|
  next accumulator.merge!(low: true) if current[:a] <= 2

  accumulator.merge!(low: false)
end

Assignment (.=) returns the assigned value, .merge! returns product hash, and the code would stop working.

Describe the solution you'd like

I'd like it to be smart enough not to suggest that, so I don't have to ignore it.

Describe alternatives you've considered

rubocop:disable Performance/RedundantMerge