ruby - 次のキーと値のペアは、新しいキーでペアを追加しようとしているときに、ハッシュ内の既存のペアを上書きします

Question

私は持っている：

fruits = {
  "orange" => {:season => "winter"},
  "apple" => {:season => "winter"},
  "banana" => {:season => "summer"},
  "grape" => {:season => "spring"},
  "peach" => {:season => "winter"},
  "pineapple" => {:season => "summer"}
}

私は手に入れたい：

{
  "winter"=>["orange", "apple", "peach"],
  "summer"=>["banana", "pineapple"],
  "spring"=>["grape"]
}

やった：

def sort_fruits(fruits_hash)
  fruits=[]
  sorted = {}
  seasons = fruits_hash.map {|k, v|v[:season]}
  seasons.uniq.each do |season|
    fruits.clear
    fruits_hash.each do |fruit, season_name|
      if season == season_name[:season]
        fruits << fruit
      end
    end
    p sorted[season] = fruits ## season changes to new season, so this should have created new key/value pair for new season.
  end
  sorted
end

私は得る：

{
  "winter"=>["grape"],
  "summer"=>["grape"],
  "spring"=>["grape"]
}

一意のキーを持つ新しいキーと値のペアを追加すると、ハッシュ内の既存のペアが上書きされる理由がわかりませんでした。説明の助けをいただければ幸いです。