Fix cache warning on heroku-22 (heroku#1588)

* Assert no warnings from `cp`

* Fix cache warning on heroku-22

Before:

```
$ be rspec spec/hatchet/getting_started_spec.rb:25
Run options: include {:focused=>true, :locations=>{"./spec/hatchet/getting_started_spec.rb"=>[25]}}
Hatchet setup: "hatchet-t-91c5d5b6ce" for "ruby-getting-started"
Destroying "hatchet-t-91c5d5b6ce": eb7dab2f-d12a-4bd2-b62a-c48781aa55a9, (0/20) reason: teardown
F

Failures:

  1) Heroku ruby getting started works on Heroku-22
     Failure/Error: expect(app.output).to_not include("cp --help")
```

After:

```
$ be rspec spec/hatchet/getting_started_spec.rb:25
Run options: include {:focused=>true, :locations=>{"./spec/hatchet/getting_started_spec.rb"=>[25]}}
Hatchet setup: "hatchet-t-17874ceca3" for "ruby-getting-started"
Finished in 2 minutes 21.4 seconds (files took 0.1802 seconds to load)
1 example, 0 failures
```

Author: schneems

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## [Unreleased]
 
+- Fix `cp --update=none` warning `heroku-22` (https://github.com/heroku/heroku-buildpack-ruby/pull/1588)
 
 ## [v304] - 2025-04-28
 

lib/language_pack/cache.rb

@@ -59,7 +59,8 @@ def load_without_overwrite(path, dest=nil)
 
     dest ||= path
 
-    if ENV["STACK"] == "heroku-20"
+    case ENV["STACK"]
+    when "heroku-20", "heroku-22"
       copy (@cache_base + path), dest, "-a -n"
     else
       copy (@cache_base + path), dest, "-a --update=none"

spec/hatchet/getting_started_spec.rb

@@ -1,14 +1,31 @@
 require_relative '../spec_helper'
 
 describe "Heroku ruby getting started" do
-  it "clears runtime cache" do
-    Hatchet::Runner.new("ruby-getting-started").deploy do |app|
+  it "works on Heroku-24" do
+    Hatchet::Runner.new("ruby-getting-started", stack: "heroku-24").deploy do |app|
+      # Assert sprockets build cache not present on runtime
       expect(app.run("ls tmp/cache/assets")).to_not match("sprockets")
+
+      # Re-deploy with cache
+      run!("git commit --allow-empty -m empty")
+      app.push!
+
+      # Assert no warnings from `cp`
+      # https://github.com/heroku/heroku-buildpack-ruby/pull/1586/files#r2064284286
+      expect(app.output).to_not include("cp --help")
+      expect(app.run("which ruby").strip).to eq("/app/bin/ruby")
     end
   end
 
-  it "works on Heroku-24" do
-    Hatchet::Runner.new("ruby-getting-started", stack: "heroku-24").deploy do |app|
+  it "works on Heroku-22" do
+    Hatchet::Runner.new("ruby-getting-started", stack: "heroku-22").deploy do |app|
+      # Re-deploy with cache
+      run!("git commit --allow-empty -m empty")
+      app.push!
+
+      # Assert no warnings from `cp`
+      # https://github.com/heroku/heroku-buildpack-ruby/pull/1586/files#r2064284286
+      expect(app.output).to_not include("cp --help")
       expect(app.run("which ruby").strip).to eq("/app/bin/ruby")
     end
   end