Remove existing from PATH when adding Gem.bindir.

Author: reitermarkus

Library/Homebrew/utils.rb

@@ -189,14 +189,11 @@ def install_gem_setup_path!(name, version = nil, executable = name)
     Gem.clear_paths
     Gem::Specification.reset
 
-    # Create GEM_HOME which may not exist yet so it exists when creating PATH.
-    FileUtils.mkdir_p Gem.bindir
-
     # Add Gem binary directory and (if missing) Ruby binary directory to PATH.
     path = PATH.new(ENV["PATH"])
     path.prepend(RUBY_BIN) if which("ruby") != RUBY_PATH
     path.prepend(Gem.bindir)
-    ENV["PATH"] = path.existing
+    ENV["PATH"] = path
 
     if Gem::Specification.find_all_by_name(name, version).empty?
       ohai "Installing or updating '#{name}' gem"