extract: Leave a hint in place of the removed bottles block

Library/Homebrew/dev-cmd/extract.rb

@@ -133,7 +133,7 @@ def run
         result.sub!("class #{class_name} < Formula", "class #{versioned_name} < Formula")
 
         # Remove bottle blocks, as they won't work.
-        result.sub!(BOTTLE_BLOCK_REGEX, "")
+        result.sub!(BOTTLE_BLOCK_REGEX, "# The bottles might be available as oci images at docker://ghcr.io/homebrew/core/#{name}:#{version}")
 
         path = destination_tap.path/"Formula/#{name}@#{version_string}.rb"
         if path.exist?

Library/Homebrew/test/dev-cmd/extract_spec.rb

@@ -63,5 +63,15 @@
       expect(path).to exist
       expect(Formulary.factory(path).version).to eq "0.2"
     end
+
+    it "notes the url where bottles might be found", :integration_test do
+      path = target[:path]/"Formula/[email protected]"
+      expect { brew "extract", "testball", target[:name] }
+        .to output(/^#{path}$/).to_stdout
+        .and not_to_output.to_stderr
+        .and be_a_success
+      expect(path).to exist
+      expect(File.read(path)).to match(%r{docker://ghcr.io/homebrew/core/testball:0.2})
+    end
   end
 end