Use ORIGINAL_PATHS over envs; reject nil PATH

Library/Homebrew/brew.rb

@@ -53,8 +53,8 @@ begin
   args = Homebrew::CLI::Parser.new.parse(ARGV.dup.freeze, ignore_invalid_options: true)
   Context.current = args.context
 
-  path = PATH.new(ENV["PATH"])
+  path = PATH.new(ENV.fetch("PATH"))
-  homebrew_path = PATH.new(ENV["HOMEBREW_PATH"])
+  homebrew_path = PATH.new(ENV.fetch("HOMEBREW_PATH"))
 
   # Add shared wrappers.
   path.prepend(HOMEBREW_SHIMS_PATH/"shared")

Library/Homebrew/cask/artifact/installer.rb

@@ -39,7 +39,7 @@ module Cask
             executable_path,
             **args,
             env: { "PATH" => PATH.new(
-              HOMEBREW_PREFIX/"bin", HOMEBREW_PREFIX/"sbin", ENV["PATH"]
+              HOMEBREW_PREFIX/"bin", HOMEBREW_PREFIX/"sbin", ENV.fetch("PATH")
             ) },
           )
         end

Library/Homebrew/caveats.rb

@@ -78,7 +78,7 @@ class Caveats
 
       s << "  #{Utils::Shell.export_value("CPPFLAGS", "-I#{f.opt_include}")}\n" if f.include.directory?
 
-      if which("pkg-config", ENV["HOMEBREW_PATH"]) &&
+      if which("pkg-config", ORIGINAL_PATHS) &&
          ((f.lib/"pkgconfig").directory? || (f.share/"pkgconfig").directory?)
         s << <<~EOS
 
@@ -109,7 +109,7 @@ class Caveats
 
   def function_completion_caveats(shell)
     return unless keg
-    return unless which(shell.to_s, ENV["HOMEBREW_PATH"])
+    return unless which(shell.to_s, ORIGINAL_PATHS)
 
     completion_installed = keg.completion_installed?(shell)
     functions_installed = keg.functions_installed?(shell)

Library/Homebrew/cleanup.rb

@@ -391,7 +391,7 @@ module Homebrew
     end
 
     def cleanup_portable_ruby
-      rubies = [which("ruby"), which("ruby", ENV["HOMEBREW_PATH"])].compact
+      rubies = [which("ruby"), which("ruby", ORIGINAL_PATHS)].compact
       system_ruby = Pathname.new("/usr/bin/ruby")
       rubies << system_ruby if system_ruby.exist?
 

Library/Homebrew/cmd/log.rb

@@ -42,7 +42,7 @@ module Homebrew
 
     # As this command is simplifying user-run commands then let's just use a
     # user path, too.
-    ENV["PATH"] = ENV["HOMEBREW_PATH"]
+    ENV["PATH"] = PATH.new(ORIGINAL_PATHS).to_s
 
     if args.no_named?
       git_log HOMEBREW_REPOSITORY, args: args

Library/Homebrew/commands.rb

@@ -93,11 +93,11 @@ module Commands
 
   # Ruby commands which are run by being `require`d.
   def external_ruby_cmd_path(cmd)
-    which("brew-#{cmd}.rb", PATH.new(ENV["PATH"]).append(Tap.cmd_directories))
+    which("brew-#{cmd}.rb", PATH.new(ENV.fetch("PATH")).append(Tap.cmd_directories))
   end
 
   def external_cmd_path(cmd)
-    which("brew-#{cmd}", PATH.new(ENV["PATH"]).append(Tap.cmd_directories))
+    which("brew-#{cmd}", PATH.new(ENV.fetch("PATH")).append(Tap.cmd_directories))
   end
 
   def path(cmd)

Library/Homebrew/dev-cmd/bump-cask-pr.rb

@@ -67,7 +67,7 @@ module Homebrew
 
     # As this command is simplifying user-run commands then let's just use a
     # user path, too.
-    ENV["PATH"] = ENV["HOMEBREW_PATH"]
+    ENV["PATH"] = PATH.new(ORIGINAL_PATHS).to_s
 
     # Use the user's browser, too.
     ENV["BROWSER"] = Homebrew::EnvConfig.browser

Library/Homebrew/dev-cmd/bump-formula-pr.rb

@@ -108,7 +108,7 @@ module Homebrew
 
     # As this command is simplifying user-run commands then let's just use a
     # user path, too.
-    ENV["PATH"] = ENV["HOMEBREW_PATH"]
+    ENV["PATH"] = PATH.new(ORIGINAL_PATHS).to_s
 
     # Use the user's browser, too.
     ENV["BROWSER"] = Homebrew::EnvConfig.browser

Library/Homebrew/dev-cmd/bump-revision.rb

@@ -36,7 +36,7 @@ module Homebrew
 
     # As this command is simplifying user-run commands then let's just use a
     # user path, too.
-    ENV["PATH"] = ENV["HOMEBREW_PATH"]
+    ENV["PATH"] = PATH.new(ORIGINAL_PATHS).to_s
 
     args.named.to_formulae.each do |formula|
       current_revision = formula.revision

Library/Homebrew/dev-cmd/sh.rb

@@ -38,7 +38,7 @@ module Homebrew
     ENV.setup_build_environment
     if superenv?(args.env)
       # superenv stopped adding brew's bin but generally users will want it
-      ENV["PATH"] = PATH.new(ENV["PATH"]).insert(1, HOMEBREW_PREFIX/"bin")
+      ENV["PATH"] = PATH.new(ENV.fetch("PATH")).insert(1, HOMEBREW_PREFIX/"bin")
     end
 
     ENV["VERBOSE"] = "1" if args.verbose?

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

@@ -123,7 +123,7 @@ module Homebrew
       safe_system "git", "reset", "--hard", start_commit
 
       # update ENV["PATH"]
-      ENV["PATH"] = PATH.new(ENV["PATH"]).prepend(curdir/"bin")
+      ENV["PATH"] = PATH.new(ENV.fetch("PATH")).prepend(curdir/"bin")
 
       # run brew help to install portable-ruby (if needed)
       quiet_system "brew", "help"

Library/Homebrew/download_strategy.rb

@@ -1139,7 +1139,7 @@ class CVSDownloadStrategy < VCSDownloadStrategy
   private
 
   def env
-    { "PATH" => PATH.new("/usr/bin", Formula["cvs"].opt_bin, ENV["PATH"]) }
+    { "PATH" => PATH.new("/usr/bin", Formula["cvs"].opt_bin, ENV.fetch("PATH")) }
   end
 
   sig { returns(String) }
@@ -1214,7 +1214,7 @@ class MercurialDownloadStrategy < VCSDownloadStrategy
   private
 
   def env
-    { "PATH" => PATH.new(Formula["mercurial"].opt_bin, ENV["PATH"]) }
+    { "PATH" => PATH.new(Formula["mercurial"].opt_bin, ENV.fetch("PATH")) }
   end
 
   sig { returns(String) }
@@ -1280,7 +1280,7 @@ class BazaarDownloadStrategy < VCSDownloadStrategy
 
   def env
     {
-      "PATH"     => PATH.new(Formula["bazaar"].opt_bin, ENV["PATH"]),
+      "PATH"     => PATH.new(Formula["bazaar"].opt_bin, ENV.fetch("PATH")),
       "BZR_HOME" => HOMEBREW_TEMP,
     }
   end
@@ -1345,7 +1345,7 @@ class FossilDownloadStrategy < VCSDownloadStrategy
   private
 
   def env
-    { "PATH" => PATH.new(Formula["fossil"].opt_bin, ENV["PATH"]) }
+    { "PATH" => PATH.new(Formula["fossil"].opt_bin, ENV.fetch("PATH")) }
   end
 
   sig { returns(String) }

Library/Homebrew/extend/ENV/std.rb

@@ -28,7 +28,7 @@ module Stdenv
 
     self["HOMEBREW_ENV"] = "std"
 
-    PATH.new(ENV["HOMEBREW_PATH"]).reverse_each { |p| prepend_path "PATH", p }
+    ORIGINAL_PATHS.reverse_each { |p| prepend_path "PATH", p }
     prepend_path "PATH", HOMEBREW_SHIMS_PATH/"shared"
 
     # Set the default pkg-config search path, overriding the built-in paths

Library/Homebrew/formula.rb

@@ -421,9 +421,9 @@ class Formula
     return unless head.downloader.cached_location.exist?
 
     path = if ENV["HOMEBREW_ENV"]
-      ENV["PATH"]
+      ENV.fetch("PATH")
     else
-      ENV["HOMEBREW_PATH"]
+      PATH.new(ORIGINAL_PATHS)
     end
 
     with_env(PATH: path) do
@@ -1103,7 +1103,7 @@ class Formula
         TMP:           HOMEBREW_TEMP,
         _JAVA_OPTIONS: "-Djava.io.tmpdir=#{HOMEBREW_TEMP}",
         HOMEBREW_PATH: nil,
-        PATH:          ENV["HOMEBREW_PATH"],
+        PATH:          PATH.new(ORIGINAL_PATHS),
       }
 
       with_env(new_env) do
@@ -2077,7 +2077,7 @@ class Formula
       TEMP:          HOMEBREW_TEMP,
       TMP:           HOMEBREW_TEMP,
       TERM:          "dumb",
-      PATH:          PATH.new(ENV["PATH"], HOMEBREW_PREFIX/"bin"),
+      PATH:          PATH.new(ENV.fetch("PATH"), HOMEBREW_PREFIX/"bin"),
       HOMEBREW_PATH: nil,
     }.merge(common_stage_test_env)
     test_env[:_JAVA_OPTIONS] += " -Djava.io.tmpdir=#{HOMEBREW_TEMP}"

Library/Homebrew/formula_cellar_checks.rb

@@ -299,7 +299,7 @@ module FormulaCellarChecks
     objdump   = Formula["llvm"].opt_bin/"llvm-objdump" if Formula["llvm"].any_version_installed?
     objdump ||= Formula["binutils"].opt_bin/"objdump" if Formula["binutils"].any_version_installed?
     objdump ||= which("objdump")
-    objdump ||= which("objdump", ENV["HOMEBREW_PATH"])
+    objdump ||= which("objdump", ORIGINAL_PATHS)
 
     unless objdump
       return <<~EOS

Library/Homebrew/global.rb

@@ -119,8 +119,8 @@ require "cli/args"
 
 require "PATH"
 
-ENV["HOMEBREW_PATH"] ||= ENV["PATH"]
+ENV["HOMEBREW_PATH"] ||= ENV.fetch("PATH")
-ORIGINAL_PATHS = PATH.new(ENV["HOMEBREW_PATH"]).map do |p|
+ORIGINAL_PATHS = PATH.new(ENV.fetch("HOMEBREW_PATH")).map do |p|
   Pathname.new(p).expand_path
 rescue
   nil

Library/Homebrew/requirement.rb

@@ -103,7 +103,7 @@ class Requirement
     parent = satisfied_result_parent
     return unless parent
     return if ["#{HOMEBREW_PREFIX}/bin", "#{HOMEBREW_PREFIX}/bin"].include?(parent.to_s)
-    return if PATH.new(ENV["PATH"]).include?(parent.to_s)
+    return if PATH.new(ENV.fetch("PATH")).include?(parent.to_s)
 
     ENV.prepend_path("PATH", parent)
   end

Library/Homebrew/test/cask/artifact/installer_spec.rb

@@ -34,7 +34,7 @@ describe Cask::Artifact::Installer, :cask do
         expect(command).to receive(:run!).with(
           executable,
           a_hash_including(
-            env: { "PATH" => PATH.new("#{HOMEBREW_PREFIX}/bin", "#{HOMEBREW_PREFIX}/sbin", ENV["PATH"]) },
+            env: { "PATH" => PATH.new("#{HOMEBREW_PREFIX}/bin", "#{HOMEBREW_PREFIX}/sbin", ENV.fetch("PATH")) },
           ),
         )
 

Library/Homebrew/test/cmd/custom-external-command_spec.rb

@@ -13,7 +13,7 @@ describe "brew custom-external-command", :integration_test do
       SH
       FileUtils.chmod "+x", file
 
-      expect { brew cmd, "PATH" => "#{path}#{File::PATH_SEPARATOR}#{ENV["PATH"]}" }
+      expect { brew cmd, "PATH" => "#{path}#{File::PATH_SEPARATOR}#{ENV.fetch("PATH")}" }
         .to output("I am #{cmd}.\n").to_stdout
         .and not_to_output.to_stderr
         .and be_a_success

Library/Homebrew/test/diagnostic_checks_spec.rb

@@ -20,7 +20,7 @@ describe Homebrew::Diagnostic::Checks do
       FileUtils.chmod 0755, anaconda
       FileUtils.chmod 0755, python
 
-      ENV["PATH"] = "#{path}#{File::PATH_SEPARATOR}#{ENV["PATH"]}"
+      ENV["PATH"] = "#{path}#{File::PATH_SEPARATOR}#{ENV.fetch("PATH")}"
 
       expect(checks.check_for_anaconda).to match("Anaconda")
     end
@@ -75,10 +75,12 @@ describe Homebrew::Diagnostic::Checks do
 
   specify "#check_user_path_3" do
     sbin = HOMEBREW_PREFIX/"sbin"
-    ENV["HOMEBREW_PATH"] =
+    (sbin/"something").mkpath
+
+    homebrew_path =
       "#{HOMEBREW_PREFIX}/bin#{File::PATH_SEPARATOR}" +
       ENV["HOMEBREW_PATH"].gsub(/(?:^|#{Regexp.escape(File::PATH_SEPARATOR)})#{Regexp.escape(sbin)}/, "")
-    (sbin/"something").mkpath
+    stub_const("ORIGINAL_PATHS", PATH.new(homebrew_path).map { |path| Pathname.new(path).expand_path }.compact)
 
     expect(checks.check_user_path_1).to be_nil
     expect(checks.check_user_path_2).to be_nil
@@ -93,8 +95,7 @@ describe Homebrew::Diagnostic::Checks do
       file = "#{path}/foo-config"
       FileUtils.touch file
       FileUtils.chmod 0755, file
-      ENV["HOMEBREW_PATH"] = ENV["PATH"] =
+      ENV["PATH"] = "#{path}#{File::PATH_SEPARATOR}#{ENV.fetch("PATH")}"
-        "#{path}#{File::PATH_SEPARATOR}#{ENV["PATH"]}"
 
       expect(checks.check_for_config_scripts)
         .to match('"config" scripts exist')

Library/Homebrew/test/spec_helper.rb

@@ -150,7 +150,7 @@ RSpec.configure do |config|
     skip "Subversion is not installed." unless quiet_system svn_shim, "--version"
 
     svn_shim_path = Pathname(Utils.popen_read(svn_shim, "--homebrew=print-path").chomp.presence)
-    svn_paths = PATH.new(ENV["PATH"])
+    svn_paths = PATH.new(ENV.fetch("PATH"))
     svn_paths.prepend(svn_shim_path.dirname)
 
     if OS.mac?
@@ -164,7 +164,7 @@ RSpec.configure do |config|
     svnadmin = which("svnadmin", svn_paths)
     skip "svnadmin is not installed." unless svnadmin
 
-    ENV["PATH"] = PATH.new(ENV["PATH"])
+    ENV["PATH"] = PATH.new(ENV.fetch("PATH"))
                       .append(svn.dirname)
                       .append(svnadmin.dirname)
   end

Library/Homebrew/test/support/helper/spec/shared_context/integration_test.rb

@@ -73,7 +73,7 @@ RSpec.shared_context "integration test" do # rubocop:disable RSpec/ContextWordin
       env["PATH"],
       (HOMEBREW_LIBRARY_PATH/"test/support/helper/cmd").realpath.to_s,
       (HOMEBREW_PREFIX/"bin").realpath.to_s,
-      ENV["PATH"],
+      ENV.fetch("PATH"),
     ].compact.join(File::PATH_SEPARATOR)
 
     env.merge!(

Library/Homebrew/test/utils_spec.rb

@@ -274,17 +274,19 @@ describe "globally-scoped helper methods" do
 
   describe "#with_env" do
     it "sets environment variables within the block" do
-      expect(ENV["PATH"]).not_to eq("/bin")
+      expect(ENV.fetch("PATH")).not_to eq("/bin")
       with_env(PATH: "/bin") do
-        expect(ENV["PATH"]).to eq("/bin")
+        expect(ENV.fetch("PATH", nil)).to eq("/bin")
       end
     end
 
     it "restores ENV after the block" do
       with_env(PATH: "/bin") do
-        expect(ENV["PATH"]).to eq("/bin")
+        expect(ENV.fetch("PATH", nil)).to eq("/bin")
       end
-      expect(ENV["PATH"]).not_to eq("/bin")
+      path = ENV.fetch("PATH", nil)
+      expect(path).not_to be_nil
+      expect(path).not_to eq("/bin")
     end
 
     it "restores ENV if an exception is raised" do
@@ -294,7 +296,9 @@ describe "globally-scoped helper methods" do
         end
       }.to raise_error(StandardError)
 
-      expect(ENV["PATH"]).not_to eq("/bin")
+      path = ENV.fetch("PATH", nil)
+      expect(path).not_to be_nil
+      expect(path).not_to eq("/bin")
     end
   end
 

Library/Homebrew/unpack_strategy/cab.rb

@@ -23,7 +23,7 @@ module UnpackStrategy
     def extract_to_dir(unpack_dir, basename:, verbose:)
       system_command! "cabextract",
                       args:    ["-d", unpack_dir, "--", path],
-                      env:     { "PATH" => PATH.new(Formula["cabextract"].opt_bin, ENV["PATH"]) },
+                      env:     { "PATH" => PATH.new(Formula["cabextract"].opt_bin, ENV.fetch("PATH")) },
                       verbose: verbose
     end
 

Library/Homebrew/unpack_strategy/fossil.rb

@@ -39,7 +39,7 @@ module UnpackStrategy
       system_command! "fossil",
                       args:    ["open", path, *args],
                       chdir:   unpack_dir,
-                      env:     { "PATH" => PATH.new(Formula["fossil"].opt_bin, ENV["PATH"]) },
+                      env:     { "PATH" => PATH.new(Formula["fossil"].opt_bin, ENV.fetch("PATH")) },
                       verbose: verbose
     end
   end

Library/Homebrew/unpack_strategy/generic_unar.rb

@@ -32,7 +32,7 @@ module UnpackStrategy
                         "-force-overwrite", "-quiet", "-no-directory",
                         "-output-directory", unpack_dir, "--", path
                       ],
-                      env:     { "PATH" => PATH.new(Formula["unar"].opt_bin, ENV["PATH"]) },
+                      env:     { "PATH" => PATH.new(Formula["unar"].opt_bin, ENV.fetch("PATH")) },
                       verbose: verbose
     end
   end

Library/Homebrew/unpack_strategy/lha.rb

@@ -29,7 +29,7 @@ module UnpackStrategy
     def extract_to_dir(unpack_dir, basename:, verbose:)
       system_command! "lha",
                       args:    ["xq2w=#{unpack_dir}", path],
-                      env:     { "PATH" => PATH.new(Formula["lha"].opt_bin, ENV["PATH"]) },
+                      env:     { "PATH" => PATH.new(Formula["lha"].opt_bin, ENV.fetch("PATH")) },
                       verbose: verbose
     end
   end

Library/Homebrew/unpack_strategy/lzip.rb

@@ -31,7 +31,7 @@ module UnpackStrategy
       quiet_flags = verbose ? [] : ["-q"]
       system_command! "lzip",
                       args:    ["-d", *quiet_flags, unpack_dir/basename],
-                      env:     { "PATH" => PATH.new(Formula["lzip"].opt_bin, ENV["PATH"]) },
+                      env:     { "PATH" => PATH.new(Formula["lzip"].opt_bin, ENV.fetch("PATH")) },
                       verbose: verbose
     end
   end

Library/Homebrew/unpack_strategy/lzma.rb

@@ -31,7 +31,7 @@ module UnpackStrategy
       quiet_flags = verbose ? [] : ["-q"]
       system_command! "unlzma",
                       args:    [*quiet_flags, "--", unpack_dir/basename],
-                      env:     { "PATH" => PATH.new(Formula["xz"].opt_bin, ENV["PATH"]) },
+                      env:     { "PATH" => PATH.new(Formula["xz"].opt_bin, ENV.fetch("PATH")) },
                       verbose: verbose
     end
   end

Library/Homebrew/unpack_strategy/mercurial.rb

@@ -17,7 +17,7 @@ module UnpackStrategy
     def extract_to_dir(unpack_dir, basename:, verbose:)
       system_command! "hg",
                       args:    ["--cwd", path, "archive", "--subrepos", "-y", "-t", "files", unpack_dir],
-                      env:     { "PATH" => PATH.new(Formula["mercurial"].opt_bin, ENV["PATH"]) },
+                      env:     { "PATH" => PATH.new(Formula["mercurial"].opt_bin, ENV.fetch("PATH")) },
                       verbose: verbose
     end
   end

Library/Homebrew/unpack_strategy/p7zip.rb

@@ -29,7 +29,7 @@ module UnpackStrategy
     def extract_to_dir(unpack_dir, basename:, verbose:)
       system_command! "7zr",
                       args:    ["x", "-y", "-bd", "-bso0", path, "-o#{unpack_dir}"],
-                      env:     { "PATH" => PATH.new(Formula["p7zip"].opt_bin, ENV["PATH"]) },
+                      env:     { "PATH" => PATH.new(Formula["p7zip"].opt_bin, ENV.fetch("PATH")) },
                       verbose: verbose
     end
   end

Library/Homebrew/unpack_strategy/rar.rb

@@ -29,7 +29,7 @@ module UnpackStrategy
     def extract_to_dir(unpack_dir, basename:, verbose:)
       system_command! "unrar",
                       args:    ["x", "-inul", path, unpack_dir],
-                      env:     { "PATH" => PATH.new(Formula["unrar"].opt_bin, ENV["PATH"]) },
+                      env:     { "PATH" => PATH.new(Formula["unrar"].opt_bin, ENV.fetch("PATH")) },
                       verbose: verbose
     end
   end

Library/Homebrew/unpack_strategy/xz.rb

@@ -31,7 +31,7 @@ module UnpackStrategy
       quiet_flags = verbose ? [] : ["-q"]
       system_command! "unxz",
                       args:    [*quiet_flags, "-T0", "--", unpack_dir/basename],
-                      env:     { "PATH" => PATH.new(Formula["xz"].opt_bin, ENV["PATH"]) },
+                      env:     { "PATH" => PATH.new(Formula["xz"].opt_bin, ENV.fetch("PATH")) },
                       verbose: verbose
     end
   end

Library/Homebrew/unpack_strategy/zip.rb

@@ -37,7 +37,7 @@ module UnpackStrategy
         quiet_flags = verbose ? [] : ["-qq"]
         result = system_command! "unzip",
                                  args:         [*quiet_flags, "-o", path, "-d", unpack_dir],
-                                 env:          { "PATH" => PATH.new(unzip&.opt_bin, ENV["PATH"]) },
+                                 env:          { "PATH" => PATH.new(unzip&.opt_bin, ENV.fetch("PATH")) },
                                  verbose:      verbose,
                                  print_stderr: false
 

Library/Homebrew/unpack_strategy/zstd.rb

@@ -31,7 +31,7 @@ module UnpackStrategy
       quiet_flags = verbose ? [] : ["-q"]
       system_command! "unzstd",
                       args:    [*quiet_flags, "-T0", "--rm", "--", unpack_dir/basename],
-                      env:     { "PATH" => PATH.new(Formula["zstd"].opt_bin, ENV["PATH"]) },
+                      env:     { "PATH" => PATH.new(Formula["zstd"].opt_bin, ENV.fetch("PATH")) },
                       verbose: verbose
     end
   end

Library/Homebrew/utils.rb

@@ -305,7 +305,7 @@ module Kernel
   end
 
   def with_homebrew_path(&block)
-    with_env(PATH: PATH.new(ENV["HOMEBREW_PATH"]), &block)
+    with_env(PATH: PATH.new(ORIGINAL_PATHS), &block)
   end
 
   def with_custom_locale(locale, &block)
@@ -329,7 +329,7 @@ module Kernel
     end
   end
 
-  def which(cmd, path = ENV["PATH"])
+  def which(cmd, path = ENV.fetch("PATH"))
     PATH.new(path).each do |p|
       begin
         pcmd = File.expand_path(cmd, p)
@@ -343,7 +343,7 @@ module Kernel
     nil
   end
 
-  def which_all(cmd, path = ENV["PATH"])
+  def which_all(cmd, path = ENV.fetch("PATH"))
     PATH.new(path).map do |p|
       begin
         pcmd = File.expand_path(cmd, p)
@@ -362,7 +362,7 @@ module Kernel
 
     # Find Atom, Sublime Text, VS Code, Textmate, BBEdit / TextWrangler, or vim
     editor = %w[atom subl code mate edit vim].find do |candidate|
-      candidate if which(candidate, ENV["HOMEBREW_PATH"])
+      candidate if which(candidate, ORIGINAL_PATHS)
     end
     editor ||= "vim"
 
@@ -499,7 +499,7 @@ module Kernel
 
     executable = [
       which(name),
-      which(name, ENV["HOMEBREW_PATH"]),
+      which(name, ORIGINAL_PATHS),
       HOMEBREW_PREFIX/"bin/#{name}",
     ].compact.first
     return executable if executable.exist?
@@ -508,11 +508,7 @@ module Kernel
   end
 
   def paths
-    @paths ||= PATH.new(ENV["HOMEBREW_PATH"]).map do |p|
+    @paths ||= ORIGINAL_PATHS.uniq.map(&:to_s)
-      File.expand_path(p).chomp("/")
-    rescue ArgumentError
-      onoe "The following PATH component is invalid: #{p}"
-    end.uniq.compact
   end
 
   def parse_author!(author)

Library/Homebrew/utils/git.rb

@@ -124,7 +124,7 @@ module Utils
       gnupg_bin = HOMEBREW_PREFIX/"opt/gnupg/bin"
       return unless gnupg_bin.directory?
 
-      ENV["PATH"] = PATH.new(ENV["PATH"])
+      ENV["PATH"] = PATH.new(ENV.fetch("PATH"))
                         .prepend(gnupg_bin)
     end