Extract package into new temporary directory.

Library/Homebrew/dev-cmd/bump-unversioned-casks.rb

@@ -198,7 +198,10 @@ module Homebrew
           .uniq
 
         if packages.count == 1
-          extract_dir = dir/pkg_path.stem
+          Dir.mktmpdir do |extract_dir|
+            extract_dir = Pathname(extract_dir)
+            FileUtils.rmdir extract_dir
+
             system_command! "pkgutil", args: ["--expand-full", pkg_path, extract_dir]
 
             package_info_path = extract_dir/"PackageInfo"
@@ -210,7 +213,7 @@ module Homebrew
               onoe "#{pkg_path.basename} does not contain a `PackageInfo` file."
               next
             end
-
+          end
         else
           opoo "Skipping, #{pkg_path.basename} contains multiple packages."
           next