From d6dc9caa022db9fcadb79b1b9d8e673eeb066917 Mon Sep 17 00:00:00 2001
From: "Yukihiro \"Matz\" Matsumoto" <matz@ruby.or.jp>
Date: Wed, 14 Dec 2022 07:39:10 +0900
Subject: [PATCH] mruby-hash-ext/hash.rb: make transform_keys! to keep old keys

```ruby
h={1=>2,2=>3}
h.transform_keys!{_1.succ}
```

used to make `h` to `{2=>2}` (duplicated keys were squashed), but now
makes it `{2=>2,3=>3}`.
---
 mrbgems/mruby-hash-ext/mrblib/hash.rb | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/mrbgems/mruby-hash-ext/mrblib/hash.rb b/mrbgems/mruby-hash-ext/mrblib/hash.rb
index 6fec1c17d..5a8b53778 100644
--- a/mrbgems/mruby-hash-ext/mrblib/hash.rb
+++ b/mrbgems/mruby-hash-ext/mrblib/hash.rb
@@ -428,12 +428,8 @@ class Hash
   #
   def transform_keys!(&block)
     return to_enum :transform_keys! unless block
-    self.keys.each do |k|
-      value = self[k]
-      self.__delete(k)
-      k = block.call(k) if block
-      self[k] = value
-    end
+    hash = self.transform_keys(&block)
+    self.replace(hash)
     self
   end
   ##