Merge pull request #6464 from idoo/master

Create '.keepme' files in directories

Library/Homebrew/install.rb

@@ -24,6 +24,12 @@ module Homebrew
       Keg::MUST_EXIST_DIRECTORIES.each do |dir|
         begin
           FileUtils.mkdir_p(dir) unless dir.exist?
+
+          # Create these files to ensure that these directories aren't removed
+          # by the Catalina installer.
+          # (https://github.com/Homebrew/brew/issues/6263)
+          keep_file = dir/".keepme"
+          FileUtils.touch(keep_file) unless keep_file.exist?
         rescue
           nil
         end