Simplify keg relocation fix with minimal changes

Co-authored-by: MikeMcQuaid <125011+MikeMcQuaid@users.noreply.github.com>

Library/Homebrew/keg_relocate.rb

@@ -128,6 +128,12 @@ class Keg
     }
   end
 
+  sig { params(file: Pathname).returns(T::Boolean) }
+  def homebrew_created_file?(file)
+    basename = file.basename.to_s
+    basename.start_with?("homebrew.") && %w[.plist .service .timer].include?(file.extname)
+  end
+
   sig { returns(Relocation) }
   def prepare_relocation_to_placeholders
     relocation = Relocation.new
@@ -251,7 +257,17 @@ class Keg
     regular_files.each do |first, *rest|
       s = first.open("rb", &:read)
 
-      next unless relocation.replace_text!(s)
+      # Use full prefix replacement for Homebrew-created files when using selective relocation
+      current_relocation = if new_usr_local_relocation? && homebrew_created_file?(first)
+        full_relocation = Relocation.new
+        full_relocation.add_replacement_pair(:prefix, HOMEBREW_PREFIX.to_s, PREFIX_PLACEHOLDER, path: true)
+        full_relocation.add_replacement_pair(:cellar, HOMEBREW_CELLAR.to_s, CELLAR_PLACEHOLDER, path: true)
+        full_relocation
+      else
+        relocation
+      end
+
+      next unless current_relocation.replace_text!(s)
 
       changed_files += [first, *rest].map { |file| file.relative_path_from(path) }
 

Library/Homebrew/test/keg_spec.rb

@@ -1,3 +1,4 @@
+# typed: strict
 # frozen_string_literal: true
 
 require "keg"
@@ -6,7 +7,7 @@ require "stringio"
 RSpec.describe Keg do
   include FileUtils
 
-  def setup_test_keg(name, version)
+  define_method(:setup_test_keg) do |name, version|
     path = HOMEBREW_CELLAR/name/version
     (path/"bin").mkpath
 
@@ -319,6 +320,29 @@ RSpec.describe Keg do
     end
   end
 
+  describe "#homebrew_created_file?" do
+    it "identifies Homebrew service files" do
+      plist_file = instance_double(Pathname, extname: ".plist", basename: Pathname.new("homebrew.foo.plist"))
+      service_file = instance_double(Pathname, extname: ".service", basename: Pathname.new("homebrew.foo.service"))
+      timer_file = instance_double(Pathname, extname: ".timer", basename: Pathname.new("homebrew.foo.timer"))
+      regular_file = instance_double(Pathname, extname: ".txt", basename: Pathname.new("readme.txt"))
+      non_homebrew_plist = instance_double(Pathname, extname:  ".plist",
+                                                     basename: Pathname.new("com.example.foo.plist"))
+
+      allow(plist_file.basename).to receive(:to_s).and_return("homebrew.foo.plist")
+      allow(service_file.basename).to receive(:to_s).and_return("homebrew.foo.service")
+      allow(timer_file.basename).to receive(:to_s).and_return("homebrew.foo.timer")
+      allow(regular_file.basename).to receive(:to_s).and_return("readme.txt")
+      allow(non_homebrew_plist.basename).to receive(:to_s).and_return("com.example.foo.plist")
+
+      expect(keg.homebrew_created_file?(plist_file)).to be true
+      expect(keg.homebrew_created_file?(service_file)).to be true
+      expect(keg.homebrew_created_file?(timer_file)).to be true
+      expect(keg.homebrew_created_file?(regular_file)).to be false
+      expect(keg.homebrew_created_file?(non_homebrew_plist)).to be false
+    end
+  end
+
   specify "#link and #unlink" do
     expect(keg).not_to be_linked
     keg.link