Merge rubygems master.

This is RC version of Rubygems 2.7.0.
  688fb7e83c

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@60133 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/rubygems/user_interaction.rb

@@ -7,11 +7,6 @@
 
 require 'rubygems/util'
 
-begin
-  require 'io/console'
-rescue LoadError
-end
-
 ##
 # Module that defines the default UserInteraction.  Any class including this
 # module will have access to the +ui+ method that returns the default UI.
@@ -314,12 +309,21 @@ class Gem::StreamUI
     password
   end
 
-  if IO.method_defined?(:noecho) then
-    def _gets_noecho
-      @ins.noecho {@ins.gets}
+  def require_io_console
+    @require_io_console ||= begin
+      begin
+        require 'io/console'
+      rescue LoadError
+      end
+      true
     end
-  elsif Gem.win_platform?
-    def _gets_noecho
+  end
+
+  def _gets_noecho
+    require_io_console
+    if IO.method_defined?(:noecho) then
+      @ins.noecho {@ins.gets}
+    elsif Gem.win_platform?
       require "Win32API"
       password = ''
 
@@ -332,9 +336,7 @@ class Gem::StreamUI
         end
       end
       password
-    end
-  else
-    def _gets_noecho
+    else
       system "stty -echo"
       begin
         @ins.gets