* lib/rubygems: Update to RubyGems master 612f85a. Notable changes:

Fixed installation and activation of git: and path: gems via
  Gem.use_gemdeps

  Improved documentation coverage

* test/rubygems:  ditto.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43845 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/rubygems/util.rb

@@ -1,4 +1,10 @@
+##
+# This module contains various utility methods as module methods.
+
 module Gem::Util
+
+  @silent_mutex = nil
+
   ##
   # Zlib::GzipReader wrapper that unzips +data+.
 
@@ -60,4 +66,56 @@ module Gem::Util
     end
   end
 
+  ##
+  # Invokes system, but silences all output.
+
+  def self.silent_system *command
+    require 'thread'
+
+    @silent_mutex ||= Mutex.new
+
+    null_device = Gem.win_platform? ? 'NUL' : '/dev/null'
+
+    @silent_mutex.synchronize do
+      begin
+        stdout = STDOUT.dup
+        stderr = STDERR.dup
+
+        STDOUT.reopen null_device, 'w'
+        STDERR.reopen null_device, 'w'
+
+        return system(*command)
+      ensure
+        STDOUT.reopen stdout
+        STDERR.reopen stderr
+      end
+    end
+  end
+
+  ##
+  # Enumerates the parents of +directory+.
+
+  def self.traverse_parents directory
+    return enum_for __method__, directory unless block_given?
+
+    here = File.expand_path directory
+    start = here
+
+    Dir.chdir start
+
+    begin
+      loop do
+        yield here
+
+        Dir.chdir '..'
+
+        return if Dir.pwd == here # toplevel
+
+        here = Dir.pwd
+      end
+    ensure
+      Dir.chdir start
+    end
+  end
+
 end